Scroll to the bottom of the main page of the Scratch forums and click the link labeled "change your signature". Alternatively, go to https://scratch.mit.edu/discuss/settings/USERNAME replacing "USERNAME" with one's username.
The link to change one's signature.
A signature is a small piece of text attached to your posts. In it, you can enter just about anything you like. Perhaps you would like to enter your favourite quote or your star sign. It's up to you! In your signature you can use BBCode if it is allowed in this particular forum. You can see the features that are allowed/enabled listed below whenever you edit your signature.

– Text on signature changing page

The page contains an editor which allows one's signature to be changed. By entering text in the box and clicking submit, a signature can be created or changed. BBCode can be used, having the ability to format text. This includes large text, colored text, bold text, and more. The green tick in the top right corner allows the new signature to be previewed before actually being set. Images are popular for use as signatures.

See Also