You shouldn't be shoving the bit in "all the way" ever. It'll be a pain in the ass to remove. Pull the bit out a smidge. Lemme clarify first.
YOU SHOULD NEVER BE PULLING THE BIT OUT MORE THAN AN EIGTH OF AN INCH. IF YOU HAVE TO, YOU NEED TO PURCHASE A LONGER BIT!
Second. It's a pattern bit. You shouldn't need to use the plunge capabilities of your router AT ALL! Set it at ONE depth, and screw the motor down (IIRC, it's a big latch that you open up, screw the motor down some, and close the latch again), then fine tune the adjustment with the depth ring, and finally, if that router has it, a little dial.
It sounds as if you're buying tools as you go along. I'm guessing that nut is a 9/16", but if you go and buy a wrench without taking along the one that already WORKS, you're silly. You also may not be able to buy just a single wrench, you might need to buy the whole friggen set.
I know you might be frustrated right now, but if that's the case, seriously, as nos suggested, just take it back NOW and get a better one to begin with. If you think the people working at the store better be able to adjust it, then stop and think about what you're expecting. You're expecting that since you're unable to get this thing set up properly by yourself, you'll take it back, and they'll do it for you. What if the setting isn't right? If the setting IS right, how do you believe those people are going to be able to figure it out? Same way as you should be able to, right? It's just something that's frustrating, not something that's the end of the world.
ALWAYS, ALWAYS, ALWAYS, ALWAYS attach pictures when you're including such a gawdawful run on sentence. Then, explain your problem in relation to the picture we'll all be looking at (both you AND us) so that we are all looking at the same thing, and the description won't be so foreign. Remember, there might not be anyone else who owns the exact same tool as you do, and we might be giving you instructions that ensure that you'll lop off a finger, toe, carbuncle, malignant growth, etc.
Seriously. Without pics, unless we've got the same thing you've got, we're working in the dark hoping we don't blow the place up
WITH pics, we can see what you're talking about. You're in luck, since nos has the same router. If HE'S talking about the same thing YOU'RE talking about, then you're golden. If not, well....
Lastly, since it's a plunge router, it CAN cut in an up/down motion, but it's not recommended except with certain bits, and there isn't a bit you should be using that would recommend cutting in that way. Oh, and I forgot one thing - CLAMP DOWN YOUR WORKPIECES AND FOR THE LOVE OF PETE, BE CAREFUL!