To install Email Signature in Gmail for iPhone/Android, please follow the following steps:
- Firstly, install the signature in Gmail web.
- In your Gmail app, make sure mobile signature is turned off. To turn it off go to Settings > Select your mail account > Signature Settings > Switch Signature to Off
- Wait for 4 hours for the web-based Gmail server to sync with your mobile device's Gmail app.
- Your signature will not show up when you compose a new email but it will be added to your email after you send it.
Good job, you! Send a test email to yourself to make sure it works.