Gmail
- Copy the signature with the "Copy signature" button.
- In Gmail, open the gear icon at the top right and click "See all settings".
- On the "General" tab, scroll down to "Signature" and click "Create new".
- Give it a name and paste the signature into the box with Ctrl+V (Cmd+V on a Mac).
- Just below, select that signature for new emails and for replies.
- Scroll to the bottom and click "Save changes". Without that, nothing is saved.