How do I know if my trailer coupler is adjusted correctly?

I grease the TT ball. I don't grease the little utility trailer ball.

I just wipe it off every now and then and re-grease. Just your cheap 'general purpose' grease that I have in the gun.

Been working for me for the last 18 years of doing this RV thing..

I've not had to adjust the latch on either of my trailers. They let loose and go on pretty easy and I can lift up the tongue of the trailer with the jack, as that's what I do to set the WD bars.

Good luck! Mitch