GFCI in garage keeps tripping when I turn on kitchen lights
It does not seem normal that a GFCI in your garage should control outlets in the living room and bedroom.  Usually, they are connected to outlets in bathrooms and/or kitchens.  Nevertheless, you should try unplugging the two cable boxes and see if the problem persists.  If it does, then the kitchen lights need to be investigated.  If it does not, then you need to investigate the outlets that are used by the cable boxes. If you are comfortable around electricity, you can take apart the outlets and/or the light fixtures and look for wiring problems such as loose wires, worn insulation, etc.  If you are not, then you should call an electrician.