How do I change which app opens Gmail attachments?

Last reviewed: September 27, 2026 · Markdown version

There is no setting inside Gmail for this. Gmail hands the file over, and your phone or your browser decides what opens it, so that is where the setting lives. Google's attachment help for computer, Android and iPhone describes opening, downloading and saving to Drive, and none of the three versions documents a choice of app inside Gmail (Open & download attachments in Gmail, read 27 September 2026).

On Android: Always or Just once

When more than one installed app can open a file, Android asks which to use. Google's Pixel help: "To choose how often you want to use the app for this action, tap Always or Just once" (Set or clear default apps on your Pixel phone or Pixel Tablet, read 27 September 2026). If you tapped Always on the wrong app, the fix is on the app, not on the file type:

Settings → Apps, then the app that keeps opening the file (tap See all apps if it is not listed).
Open by default → Clear default preferences.

Google says that afterwards "when you take that action again, your device will ask you which app to use". These are Pixel steps and some "only work on Android 14 and up"; Samsung and other makers name the menus their own way. For web links, as opposed to files, the setting is Default apps → Browser app (Learn how to change your default browser, read 27 September 2026).

On iPhone: per file, not per type

Apple's Default Apps screen covers things like email, messaging, calling, browsing, passwords and keyboards; neither Apple page we read lists a default for opening documents or file types (Change the default apps on iPhone and Change your default apps for features on iPhone and iPad, both read 27 September 2026). So on an iPhone you choose each time. In Apple's Mail app, touch and hold the attachment and "Open it with another app: Tap Share, then choose the app" (Download email attachments in Mail on iPhone, read 27 September 2026). In the Gmail app, Google's iPhone steps for a photo end in Download, Drive, Photos or Share, and for PDFs and other files in Save to Drive (the Open & download attachments page, iPhone version).

On a computer: the browser's PDF setting

In Gmail on the web, what happens after you click Download is up to the browser. Chrome has a specific switch for PDFs: Settings → Privacy and security → Site Settings → Additional content settings → PDF documents, then "Download PDFs or Open PDFs in Chrome" (Download a file, Chrome Help, read 27 September 2026).

Two more lines from that page explain most surprises. A file opened from Chrome's download list "will open in your computer's default application for the file type", so that part is a Windows or macOS setting, not a Gmail one. And if a type now opens by itself every time, find it in the download history, right-click, and untick "Always open files of this type".

Office files have one Gmail-side option: hover over the attachment and choose Edit with Google Docs, Sheets or Slides. Google notes that "A copy of the new Office attachment is stored in Drive" (the Open & download attachments page, computer version). By our reading, that is a second copy counting toward your storage.

Before you set a default for everything

Choosing Always means the phone stops asking, including for a file you did not expect. Gmail already warns about attachments it cannot check, such as password-protected documents that "can't be scanned for viruses" (the Open & download attachments page); a warning is a good moment for the question to come back. What Gmail checks, and what it does not.