Okay, here's my problem:

In Stellar Master Mode, no matter which joint I go to, there are the descriptions of the challenges, right? Well what's the NG or NS that is by some of the challenges? Others say OK, but this doesn't. And I can't complete them.

I also was stupid enough to not read the directions when I first started playing. The manual says nothing, and I can't seem to find the on-screen directions. Please help, and if you need me to explain more, then tell me.

OK means you can change the Options for each song however you like unless you have to use specific options. NG means you cannot change any options, you must set everything to default.

So if I leave everything alone, even if it says to change something, then it will count it as completed?

If something has to be changed, no. If that's the case, change only the options it says to use. For example, if you have to clear a song on x1.5 speed, only change the speed to x1.5 and leave everything else alone (default).

Okay thank you! ^^

And if you're smart, you'll notice you can complete multiple trials at the same time if you know how to set things up.