You are probably right. I've been a member for some time but never used the signature function early on. When I did start using it I had to check the box each time I wanted to use it in a post.
Dear forum admin:
Somewhere there is a page of code that describes my personal settings. There are both settings to display others signatures, and settings to add your own signature to posts.
Please change all such settings to "true" or "1" or however it's worded, for me. Thx.