I always jack up the tire I am working on. To tighten brakes I ratchet the adjuster wheel up a notch or two at a time, I rotate the tire and repeat until the tire spins maybe one and a half to two revolutions. Depends on how hard you spin but should move and might hear slight drag.
To back off the brake shoes I push straight in and hold the locking/self-adjusting arm off while turning the adjuster wheel the other way.
I bet there is a really nice UTube video that would show you what you are trying to do (all brake drums work the same). With the tire and drum off it all looks so easy but while your lying on your back with a flash light in your mouth a screwdriver pushing the arm and a brake tool ratcheting on the teeth it all gets a little tougher.
It does sound like after the brakes are adjusted properly you need to adjust your brake controller’s sensitivity. I do minor adjustments to my controller almost every trip, my brakes seem to be a little grabby after the camper has sat for a while and as road conditions change(traffic, rain, gravel road, downhill mountains….).
2011 Wildwood T26BHXL
2004 Yukon XL Denali
43yrs of camping; one lucky guy