Thank you! I wasn't quite sure how I'd do it.

put a H command where you want the bar to end
you need to put it in each phrase you want in a different time signature

for 9/8 specifically since you can't have 18 steps in a phrase you could put a H command on row 9 and just have two phrases for each bar of music
or put a H command on row 9 and change the main groove from 6/6 to C/C (this doubles the length of each step)

So can somebody explain to me how you would go about writing a song in a different time signature in LSDJ? Like what if I wanted to do something in like 3/4 or 9/8?