Can I switch jobs after 1 week? PLEASE help me! (Target Employee)?

BELOW IS ALOT OF RAMBLING BUT ITS ESSENTIAL BACKSTORY/INFO SO THAT YOU UNDERSTAND THE SITUATION. Sorry if the organization in the writing isn't all that great. So recently after a short search for my first job I was able to get a job at Target as a cashier, before I was offered the position I was just looking for any kind of work and I didn't really care about what the duties were. Now having worked as a cashier for a week I realize that it really sucks! Its sooo boring and I dont slack off either, Im very hard working and Im always trying to get the highest score possible (we're timed on speed) but the managers keep trying to push this whole target redcard/credit card thing and the simple fact of the matter is that most people just dont want one! Then on top of that theyre trying to blame it on me as if though im not trying when clearly im trying multiple methods on every customer. Anyway im about to tell them all that their losers who've done nothing with their life seeing as they're all 40 yrs old and still working at target and thats not to mention the other douchebag cashiers who are 30 yrs old. Obviously I dont want to be disrespectful so Ive refrained from saying all that to their face. (Im 18 btw and Im headed off to college in August) ANYWAY I wanted to know whether or not it was appropriate for me to look for another job and abruptly quit at Target, the dilemma is that I know I have to leave this city/state for college in August so Ill be quitting whatever job it is that I have at that time anyway. So do you think its worth it for me to quit Target and search for another job that I know Ill only have for the summer? Or should I just stick it out at Target till I have to leave for college? What would you do? Thanks in advance Oh yea, one thing I forgot to say is that being a cashier and lifting everyones grocerys (its a Super Target) and heavy items is REALLY killing my lower back and legs to the point where, after work, I feel like im going to injure myself just trying to sit down in my car.