These are instructions based on my laptop, so maybe different on a phone or tablet, but I hope this helps. From a laptop: go to "Settings" (top right) then scroll down to "My Settings" (on the left) and look under "My Account." Click on "General Settings" under there, and it'll give you a bunch of options, including check boxes for seeing emails, private messages, etc. If you scroll down to "Thread Display Options" (now showing on the right) it'll give you boxes to check or uncheck for showing signatures, avatars, posts per page, etc. Hope this helps. It took me awhile to find it too.
thank you!!!!