How do i make a balanced pb comparison?

what do you mean by "balanced pb"? to my knowledge, there's no such feature on Livesplit (other than best segment and average segments). The only way to do so it's to make your own "balance pb" splits on Livesplit, and compare that to your recent pb / best segment.

go to settings --> choose active comparisons --> check "balanced PB" and then just select it as current comparison (either with the hotkeys to change comparisons or rightclick -> compare against)