Alarm works on and off

i replaced the batteries on the key fob thinking they were weak but that didint fix it , the alarm works fine but the key fob works when it wants to sometimes i'd have to point it really close to the rearview mirror for it to dissable or enable the alarm , i've heard about the fuse link but dont know where it is and what it does

It's not the remote... it's the alarm... particularly the reception problem. It also cost more to fix this than to get a better aftermarket alarm.