I usually walk the course 2 or 3 times (always visualizing what I'm going to do and sometimes I'll even have my hands in the right position pretending to turn). It may seem silly but so far it's worked for me. :)
I walk the course then stand in the middle of the arena and imagine going round it 2 times then I mount my horse outside the arena and watch 4 or 5 others go around the course and then I move away from the arena and picture me going around the course in my head and usually by then I have it stuck in my head 😋
Memorize lines or groups of 3 to 4 jumps. Then you ride in sections. Like. Outside line to bending line to combination to diagonal line etc. Helps a lot
Name the jumps, if one is red and white call it candy cane. If it has barrels say barrel jump. It can be a quick way to remember jumps
I'm a visual learner, so I picture myself on my horse going through the course. After I do that a few times I also like to repeat my course out loud.
I wish I was better at remembering them! But I do think it's helpful to snap a picture of the map with my phone so I can walk around (or even rotate it) and quiz myself.
I find people I can just say the course out loud too who can also say if I'm wrong.
I learn the corse near the corse map to make sure I have it right. If I have extra time (it's an important night event) I will walk around the arena and go over it from several different viewpoints
Say the jump set up out loud and make it simple. Example: gate, three strides, purple, one, yellow, right to Red... Etc