Hi and welcome!

As Gee says, it can be quite difficult to get your title changed - been there, done that.  Have you spoken to your boss and to the HR Department?  Another thing that might help in terms of recognition by your peers - you've written your job title above as "Sr. Staff Assistant".  Do you actually sign yourself off on that on letters & emails etc or is it written in full ie "Senior".  If the former, I would start writing it in full.  It's just a small thing, but could be significant.  Incidentally, are you Assistant to Senior Staff or are you a Senior amongst staff assistants?  People read things differently ...

I've sometimes found that people refer to us as "So & So's PA" in quite a dismissive tone (as annoying as being "just a secretary" - Just A really doesn't do it justice) so I will ALWAYS say and write the term in full and sometimes drop the "Personal" and go for "Assistant".  They are little things, and can be quite petty, but we sometimes have to fight for the smallest recognition.