To make changes to your signature, follow these steps:
STEP 1. Find your Avatar in the upper right hand corner of your screen.
Click on the down arrow at the end.
STEP 2. On the Drop Down Menu, under SETTINGS, Click on Account Settings.
STEP 3. This will open up the Settings screen where you will Click on the Signature icon.
STEP 4. On the right hand side of the screen, you can type the text you wish to add, and if you want to add a picture, be sure to FIRST save it to your computer so you can find it when you Click the choose files.... option.
AND REMEMBER TO SAVE YOUR CHANGES.