you cant change the top. The metallic piece is screwed to the main part of the shifter, and then the gear number piece is glued on top blocking off the screw head. Found this out the hard way; the screw somehow came loose and the top section came off. I tried removing the clear piece on top, but nothing worked. Putting it in the oven ruined it

 

if it was just glue...you could have tried something like 100% acetone. It's removed any kind of glue I've ever needed it to.