toilet install

I'm sure this has been addressed a million times so please indulge me:

I'm installing a toilet in my basement washroom. I should say, trying to install a toilet in my washroom. Each time I put the toilet down and start tightening up the t-bolts they don't seem to tighten then, before I know it, they have pulled up both sides of the closet flange bolt holder. I know this because I have taken the toilet up three times now!

How tight are the nuts on these bolts supposed to be? It seems that you should tighten until resistance is felt but these puppies just want to keep on turning. What is causing this and do they need to be tightened to hold the toilet in place? I noticed the right side is off level so I have shimmed that side but that hasn't done anything. I even raised the closet flange with a 1/4" extender flange. I also held the top of the bolt with pliers as I was tightening the nut to avoid the bolt from turning. I really am at a loss here!

Thoughts, as always, greatly appreciated

PS: I really want to have this toilet installed as I really have to go!!!

before putting the toilet down.. look at the flange(the part that the bolt is suppose to go into.. put the bolt into the metal flange and see how it is to be installed and put the nut on and turn it and see why the bolt is turning.. on mine when i did it the flange held the bolt down.. it slid into a hole on the side area and then when put in position by the toilet it was kinda locked in place by the force of the nut bringing the flange and the toilet together.. do you have the correct bolts and nut for the flange and the correct flange??? is the flange installed correctly so the bolts can be installed into the opening to put the bolts into and then slid over to the sides where the toilet holes for the bolts line up to the bolts????