clifford 750iq

I bought my car with a Clifford 750IQ. My issue is that sometimes I come back to my car and it's unlocked and the hatch is open. I'm pretty sure someone who parks near me has a remote for their car that also unlocks mine. Can I change some setting so that my remote works on a different code or something to that effect? If so, how? Sorry for sounding newbish. I have a lot of experience with car audio, but I've never had an aftermarket alarm before. Thanks for any help.

With access to the owner's manual, you can erase your remotes and reprogramme them. Except if the alarm hasn't been turned off, that's not the reason or the answer. What car please?

The car is a 2003 Nissan 350z. Unfortunately, I don't have the owner's manual for the alarm system. It didn't come with the car.

You can look up the guide online. Google it. I found mine. I just need the install for my 2000 Durango instead of paying 150 bucks to get it installed.

You didn't answer my first question. If it just unlocked the doors but didn't turn off the alarm, erasing etc. the remotes will make no difference, you're looking at a car NOT alarm related problem, also do you perchance shove the remote into a tight pocket when leaving the car? Can't tell you how often I've remote started my car by mistake.