How to add a signature on your desktop
Step 1: Launch your favorite browser and log into your Gmail account as you normally would.
Step 2: Next, click the cog icon in the upper-right corner of the screen and click Settings from the drop-down menu.
Step 3: Under the General tab, scroll down until you see Signature. Click the bubble beneath No signature, and enter whatever information you want in the signature box. You can also add a logo or image here, if desired
Optional: Below the signature field, you’ll see a checkbox that allows you to add your signature before quoted text in email replies. This will make your signature more visible in email threads. It’s worth toggling on if you’re using your email for professional correspondences, or if you want your signature to remain visible in follow-up messages.