Ok so you change the
and when you save the file then compile it again, it's still the same?
#define APPNAME ExternalBoxEsp 4.3.2_MOD
Sounds like you missed a step there.
Make sure you save it after you make that change and then compile it, also maybe change the MUTEX as well. I'm not sure what's going on, if you are in fact doing everything right, then it sounds like Windows is caching the name. Changing both APPNAME and MUTEX should fix those issues.