If you want them to look bunched up just above your heel, ok this is hard to explain, but instead of folding them just let them fall their full length, pull them down their full length or whatever, then pull it up to where you want it, no folding, and scrunch the extra up so it looks bunchy, my god this is hard to explain lol!! It should stay where you put it because its skinny so it should be tight on your leg right, well mine are lol but I buy my clothes tight so maybe this is no help. Anyway I did my best trying to explain
Its all over my head for me lol I just wear my skinnies with boots, or roll them up some in the summer and wear flip flops. The heels look isn't quite my style, looked funny to me lol, but I love it on other people, and I bunch up my friends jeans when she wears heels just like what you are talkin about but it seems impossible to explain lol but it looks good!!