Two important questions: when people try to join the forum, it welcomes them as MY username and asks them to login. Why is that? And, there is not a “register” button for them to register, only a “Login” button. Help???
are you sure it does this on any computer? or just your computer? asking because you may have the option for cookie storage turned on to prevent users from posting as guests. but wouldnt happen on other computers because they wont have the cookie where they logged in as you. you can turn that option off on forum – options – member settings…
as to register, have you enabled registrations on your blog??? check in your wp general settings…
Hi, yes I found out about it because other people contacted me saying they couldn’t register, and that it was welcoming them as ME! Also I do have registrations turned on yet there is no register button 
I hope the mods/creators here can tell me how to fix this.
Update: Register button is showing now. However, it is still welcoming other people back as me, and asking them to login as me.. ??
It looks like you are getting some JQuery errors from pinterest plugin and the page is being cached by WP-Super-Cache.
I would start with turning off caching on the forums page and then check for errors.
Let us know if this still happens please? And ask your users who may see this to take a screenshot if they will and then send it to us.