How to add or change an email signature in Gmail

• If you want your signature to show up automatically every time you compose a new message, select your signature from the drop-down menu in Signature defaults. You can have different signatures for new emails and for replies/forwards.
• Once your Gmail signature is ready, scroll down to the bottom of the page and click Save Changes.
• Go to Inbox, and open a new message window by clicking the Compose button to check if your signature shows up correctly. Use the pen icon to select different Gmail email signatures depending on a situation (if you created more than one email signature).
  Note: If in the Gmail’s message composer you have the Plain text mode enabled, you will not be able to use email signature with images, social media icons, or hyperlinks. So to disable the Plain Text mode, click More option (three dots) and deselect the Plain text mode option. You may need to wait a couple of seconds for the changes to apply. You may also need to reload your signature if it was already changed to the Plain Text format.