Have you heard back yet? For one thing, don't count chickens before you get eggs. You may not even get the job offer. I assume you want this job (at this store) right? If you go talk to them now, it could very well mess up getting into the door at all.
You should wait til they call you and tell you they want you. Now they may very well ask you right then which dept you want to work at, so you may not even have the dilemma that you think you have. Now it's also possible that they only say they want you for #1. That's when you should thank them for the offer, and tell them you are also interested in working for them (in terms of working for the store). Then follow that you should bring up the conversation you had with them back then, about other dept, ie. 2, 3, 4. Now you should prepare something to say about why you are a better fit for 2, 3, or 4, compared to 1. Employers want what works best for them, but also want workers to be happy too...otherwise they get low productivity. So if you can convince them that you'll do more for the place in 2/3/4 compared to 1, then they may be glad to have you in 2/3/4. Be persuasive but not pushy, and see if that resonates with the hiring mgr. If there's any resistance, then you may loose the offer if they only really want people for #1. In that case, then you should think about whether you really want to work #1 there in that store.
If you want to chance it, you can be proactive, and go back and ask them if they've made a decision yet. This is a fairly legit thing to ask. And, no matter the answer, you have the same conversation as above. But you got to do it with good tact, because it may make you look overconfident when you don't even have an offer from the store.