I use a quarter to adjust mine, so it may be stuck. Usually it take a little bit of pressure to turn, but not that much.
If your rifle has not been bore sighted, and even if it has been bore sighted, I might start at a 25yd range to make sure its on paper. Sight it dead on at 25, then move over to the 100 yd range. Some people will do groups of 3 for every adjustment they make. I usually only do this once I feel I'm close to where I want to be, i.e. I'll shoot once then adjust until I get it sighted an inch high at 100 yds, then I'll shoot it 3x to make sure it is in fact sighted in, if it isn't then I'll adjust and shoot 3x more.
If you've never sighted in a gun before, you might want to take an extra box or two of ammo with you, in case it takes you a box to figure things out.
Also, optics are important. If you feel like your scope is trash, have somebody look at it and if necessary replace it. If you buy a scope from a place like Gander MT or your local gun shop, they may mount it and bore sight it in for you.
Other than that, have fun and welcome to the wonderful world of rifle ownership, where you always want another rifle in some other caliber and you hardly know why.
It's a fact that 70 percent of the people who purchase heavier tackle do so with the categorical I just lost a huge snook! Einstein Hairdo.The other 30 percent have either Tarpon Fever or are sporting a hand cramped into a claw from a deepwater grouper.