Ever since i brought my amp home, i've been hearing ridiculous amounts of bass... I have to turn the bass to around 2 so it isnt ridiculously overpowering.

Could the problem be because i'm using two guitar cables as a connection from the head to cab, or does it make a difference?
Some amps and cabs do have different tones (the higher bass you are getting), if seems that something is wrong its probably because you should be using speaker cables from amp to head and not guitar cables, try it out
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Ahh dude! Don't ever use a guitar cable to connect the cab and head!
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^ it wouldnt make the tone too different though.

Why not just leave the Bass at 2 and call it a day?
It could also have something to do with the difference in acoustics of the music store and of his bedroom.
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^+1. I know when I play my combo amp in my small back room the amounts of bass is horrible, and like you i have to turn it all the way down, but when im outside or in the shed no probs at all>
yeah, definitely don't use regular shielded instrument cable for the head to cab. They make speaker cable specifically for this, and it will be labeled as such. It's a lot thicker guage wire because of the actively powered signal going to your speakers.
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it's probibally a mix of the cable and the room, im sure the guitar store is larger then your room, and the bass will bounch off the walls in your room

but dont use an instrument cable for speaker cabels......