Email signatures for Gmail can only be added via the web app (browser) on a desktop. Once you’ve added it on the desktop, it automatically syncs with the Gmail mobile app. Please refer to this documentation on how to add it via the web app browser:
If you are not seeing your signature when sending emails via the Gmail app, this is because your mobile signature is turned on in the Gmail app. To turn it off do the following:
- On your mobile device, open the Gmail app.
- Tap the Hamburger menu on the top left of the screen.
- Scroll to the bottom, then tap Settings.
- Tap your email account.
- Tap Signature settings.
- Switch the 'Signature' setting to off.
- To save, tap back arrow (top left of screen).
You are now set up and ready to go!