For starters, since it's new, remember that your shop should be glad to fix the bug for you and will be annoyed if you fiddle with the screws and then fall back on them
The screws simply act as stops to limit how far the cable can move the derailleur's cage in and out, so they are actually a set-once-and-leave-alone thing, like the idle-speed limiter on a carbuerator. It's more likely to be the alignment and/or cable adjustment.
If you'd like a full rundown on adjusting a front derailleur, check out
Park Tool's guide to FD adjustment. I also posted some troubleshooting ideas in a thread
here. But as I say, your shop should be happy to de-bug this for you.
BTW, I read your other thread, glad to see you finally have a nice bike again!
