Acetone will tend to smear the wax. There is a better product for getting it off. I don't recall what it is, but it shouldn't be too tough to find.
Tape along the top of your old decals with masking tape so you can get the new ones liked up. Tape the new ones along the line, then cut vertically between the individual letters. Apply top down with a plastic "spatula." If done correctly, no soapy water required.
/bear in mind, this is one of those jobs I would happily pay someone else to do.
Previous: 1993 Prostar 205
Red 1998 Ski Nautique, PCM GT40, 310 hp, , Acme 4 blade, Perfect Pass SG/Zbox.
Be kind. Have fun.