Unending Mac issues that Applecare can't figure out

@Gary Scotland replied to this earlier, and it was automatically marked correct, so I couldn't respond.

The problem is: NOT for me.

I have not been able to use my brand new Mac normally since August of 2015. I do a clean erase and reinstall. Within hours, I am experiencing glitches with TextEdit, apps appearing to be closed, but are not when (as I always have to) I resort to Force Quit for one app or another, because they are malfunctioning.

I do not reinstall anything from Time Capsule, so there are no old files to mess up my system. This happens within two hours of me using normal Apple applications, downloading images, and downloading Keynote to build elearning modules.

Glitches begin to creep in, and within a day, I'm as corrupted as I ever was since last August. This is after 45 erase and clean installs. Applecare cannot help me. Nobody can.

But something—SOMETHING—is wrong with my Mac!

My computer life (which is 90% of my day) is a hellhole, and I am always starting and restarting, or resetting the PRAM just to get another hour of work out of it.

Does anybody have any suggestions? AppleCare does not.

I am going to double-post this, because the problem is so overwhelming. I don't want it just in Keynote.

I apologize in advance.