I think this is the setting lever (arrowed) try depressing it with a sharpened pegwood (and not by calling it names). If that don't work can you post the same photo again but with the crown pulled out to the setting position.
Thought this manual and parts listing may be some use. Also have the 2032 and 2035 manual though quality could be better.
Vich
Tissot 2031 Manual.pdf
4256_Tissot 2031,2037.pdf