Working Posture and Abs

I have found that I have major tightness in my quads and my lower back. I am using a lacrosse ball and forma roller to get rid of all the knots there.

I am also stretching and trying to work my abs.

The ab part is where I have questions:

when I do planks, and I’m in the position, my abs drop down a bit and stick out and aren’t nice and concaved. Is that bad?
I try to suck them in but its hard and while they feel sucked in, they don’t look it…

and when I do crunches or any exercise no matter how hard I tried they pop out at the peak (contraction) of the exercise. The exercise is definitely harder when I have my stomach sucked in and my back has no arch, but it comes up as I reach the top.

is this normal, or they are so weak they won’t stay in?

what can I do to keep them tucked in when I do ab exercises?

I don’t want them popped out!

You’re supposed to hold them tight. They are likely weak and you need to try an easier variant before doing a full plank or you may be too unco to do the movement. In which case, one cue is to cough.

So get in position, cough and then hold everything in the top of the cough.

i try to hold them tight but they sag slightly.

sometimes I stand upright, exhale all the way and hold that stomach position. then i go into the plank. it feels right and they feel tight, but when I look down they are popped out somewhat.