I just got my new united seatpost and tried putting on my kris holm fusion saddle but the bracket slots are much bigger than the actual screws that should go in them, therefore, it slides. Do I just need to tighten them, or is it supposed to do that,or did I pick the wrong seatpost?
You just slide the seat to your preference, and then tighten the nuts until it doesn’t move.
Thank you!
No problem. 
Dont over tighten!!! You will regret it.