[Chriis]

A while back i had to change the trunk lock and now my alarm goes off every time i lock it.

 

[repairman54]

Could be the trunk latch out of adjustment or a issue with the latch.
A full code scan would pinpoint it not just a P code scan. Scan of all 4 code families is step one on modern vehicles and scan tool able to do it is mandatory for DIY.