A default app is the program your device automatically opens when you click on a certain type of file
When you click on a photo, your device needs to know which program to use. A default app is the program your operating system has been set to open for that job. If you click a PDF and it opens in Adobe Reader instead of your web browser, that is because Adobe Reader is set as your default PDF reader. You can change which program is the default for any file type — photos, documents, videos, email links, and more.
Default apps exist because most file types can open in multiple programs. A photo file can open in your camera app, a photo editor, a web browser, or a file viewer. Your device needs a rule for what to do when you just double-click the file without choosing a program first. That rule is the default app.
The reason this matters is control. If you prefer one program over another, or if you want to use a program that respects your privacy better than the one your device chose for you, you can change the default. You are not locked into what came with your device.
Key Takeaways
- A default app is the program that opens automatically when you click on a file type, such as a photo or a web link.
- Most file types can open in several different programs, so your device needs a default rule for each one.
- You can change the default app for any file type in your device settings, usually in a section called "Apps" or "Default Apps".
- Changing defaults does not delete the other programs — it only changes which one opens when you click a file without choosing a program first.
- Some programs try to set themselves as the default when you install them, so checking your defaults occasionally helps you keep control of your device.
How default apps are set on Windows, Mac, and mobile devices
On Windows 10 and 11, go to Settings, then Apps, then Default Apps. You will see a list of file types and the program currently set as the default for each one. Click on any file type to see other programs that can open it, and select the one you want.
On Mac, right-click any file of the type you want to change. Select "Get Info" from the menu. In the window that opens, find "Open with" and click the dropdown. Choose the program you want, then click "Change All" to set it as the default for all files of that type.
On iPhone and iPad, go to Settings, scroll down to find the app you want to set as default (such as Mail or Safari), and look for a "Default Mail App" or "Default Browser" option. Not all apps offer this choice — only apps that Apple allows to be defaults.
On Android, go to Settings, then Apps, then Default Apps (or sometimes "App Defaults"). Select the file type or action you want to change, and choose which program to use. Some Android devices also let you set defaults by opening a file, choosing a program, and checking a box that says "Always use this app".
Why some programs change your defaults without asking
When you install a new program, it sometimes automatically sets itself as the default for the file types it can open. A web browser you just downloaded might set itself as the default for opening web links. A photo editor might set itself as the default for opening image files. This happens without a dialog asking your permission.
This behavior is intentional. Programs do this because being the default app means you will use them more often — you will click a file and their program opens, which keeps you in their ecosystem. Some programs are more aggressive about this than others. Microsoft Edge, which comes with Windows, tries to become the default browser when you upgrade Windows. Google Chrome does the same when you install it.
You are not stuck with these changes. Check your defaults occasionally, especially after installing a new program. If you find a program has taken over a default you did not want to change, you can switch it back in a few seconds using the steps above.
The privacy and security angle of choosing your own defaults
Your choice of default app can affect what data your device shares. If you set a privacy-focused web browser as your default, links will open there instead of in a browser that tracks your browsing more heavily. If you set a straightforward photo viewer as your default instead of a cloud-connected photo app, your photos stay local to your device rather than being sent to a company's servers.
Default apps also matter for email. If you click an email link on a website, your default email app opens. If your default is Gmail in a web browser, that link will open Gmail and you will be logged in. If your default is a local email client that does not sync to the cloud, the link will open there instead. Neither choice is wrong — it depends on what you prefer.
Security-wise, keeping your defaults updated matters. If you stop using a program but it is still set as a default, and that program stops receiving security updates, you could be opening files in software that no longer patches vulnerabilities. Checking your defaults when you uninstall programs helps prevent this.
What happens if you do not set a default
If no default is set for a file type, your device will usually ask you to choose a program every time you click that file type. On Windows, a dialog box appears asking "How do you want to open this file?" On Mac, a similar window appears. On mobile devices, you usually see a list of programs that can open the file.
This can be useful if you use different programs for the same file type depending on what you are doing. You might open some PDFs in your web browser and others in a dedicated PDF reader. Leaving the default unset means you choose each time.
However, most people find it faster to set a default so they do not have to choose every time. The choice is yours — you can always change it back if you decide you want to be asked each time instead.
Changing defaults for specific file types versus entire programs
Most devices let you set defaults by file type. You can set one program as the default for opening PDFs, another for opening Word documents, and a third for opening photos. This gives you fine control.
Some devices also let you set defaults by action. On Windows, you can set a default program for opening web links, opening email links, or playing music files — separate from which program opens a .pdf or .docx file. On Android, you can set a default SMS app, a default phone app, and a default launcher (the program that shows your home screen).
A few programs try to set themselves as the default for everything they can handle when you install them. This is less common now than it used to be, but it still happens. If you notice a program has taken over multiple defaults you did not intend to change, you can go through and reset each one individually.
What to do if a program will not let you change the default
On Windows and Mac, you should always be able to change the default app for any file type. If a dialog is not letting you, try right-clicking the file instead of using the Settings menu, or restart your device and try again.
On iPhone, Apple restricts which apps can be set as defaults. You can set a different web browser or email app as the default, but you cannot set a third-party app as the default for opening certain file types. This is a limitation of iOS, not something you can work around.
On Android, most file types can have their defaults changed, but some system functions (like the default launcher or the default phone app) may be locked depending on your device manufacturer or carrier. Check your device settings to see what options are available to you.
Frequently Asked Questions
If I change my default app, does the old program get deleted?
No. Changing the default app only changes which program opens when you click a file. The old program stays on your device. You can still open it manually and use it whenever you want. You can also change the default back anytime.
Can I set different defaults for different file types?
Yes. You can set one program as the default for PDFs, another for photos, and a third for Word documents. Most devices let you control each file type separately, so you have full flexibility.
Why does my device keep asking me to choose a program instead of opening one automatically?
This usually means no default has been set for that file type. Go to your default apps settings and choose a program for that file type. If you prefer to choose each time, you can leave it unset and your device will keep asking.
What if I want to use a different program just this one time?
Right-click the file and select "Open with" (Windows) or "Open with" from the menu (Mac). Choose the program you want for that single file. Your default will not change.
Do I need to restart my device after changing a default app?
Usually not. The change takes effect when ready on most devices. If a program does not seem to be opening as the default after you change it, try restarting your device once.