Hey could i change any thing about my job? Like changing Mercenary Alchemist to Former State Alchemist and still have the title?

I think it would be best to stick with one career/job but I guess it depends really.
You can be a former state alchemist and be currently a mercenary, that is acceptable.

Ok so can i do it? Because i have my character carry around the watch and show it off for authority even though he has none.

Well normally they would take away the watch if you quit/get fired but I'm sure stealing it is possible lol. Yeah, you can do it.