I hate when this happens

I hate that too. usually if i anticipate it, I will just stay on the toilet for an extended amount of time in hopes I can make it one trip instead of two. Sometimes I swear that getting up triggers the urge to pass the rest so it can be faster to just go through the process and sit back down

Maybe you could try pooping like a turtle and taking your time?

I'm sure standing up triggers it for me too. It's funny that you guys mention this.

Inflammation is usually the cause of the multiple trip thing (once poop hits inflamed tissue it is uncomfortable and we must evacuate it, before all of it reaches the rectum). A few small things that help me fully evacuate while sitting on the toilet, funny as it sounds:
1.) Rubbing my abdomen in a clockwise motion, right where the large intestine is, seems to help stimulate the muscles and get things moving while sitting on the toilet.
2.) Elevating my feet, to emulate a squatting position (e.g., squatty-potty) while sitting on the toilet. Use a pile of books, small child's foot stool, or whatever you have available.
3.) Stretches that stimulate abdominal muscles before or while sitting on the toilet. Some have mentioned specific yoga poses that do this but I'm no yoga expert lol. For example, I stretch my arms, straight above my head with my hands clasped. Without bending my arms, I swing in axe chopping motion (hands still clasped) and repeat. I feel it in the abs. And stimulating that area seems to help move things along.
4.) Sitting longer than necessary on the toilet, just to make sure there isn't a little more bm just lagging behind in there lol.

Inflammation may temporarily cause thickening of intestine walls, but even those of is in remission can benefit. As longterm uc inflammation (even after temporary is gone) results in a permanent thickening of the intestinal walls, making complete evacuation more difficult. As thicker walls make the intestine less flexible, and the muscles must work harder.

IMO, you still have some inflammation. In full remission bms are neither urgent nor multi-poops. Try not to get discouraged about that, but maybe keep a food diary for a few weeks to gauge whether you "perform" better after some meals compared to others. (Assuming you're sticking with Rx meds.) / Old Hat (34 yrs with left-sided UC; presently in remission taking brandname Colazal)