help! i can't rinse out all the product in my hair

hey guys, i hope someone here can help me.

So since a few years i have this problem and off: i can't rinse out all the product in my hair when i'm washing my hair. i have changed shampoo multiple times, looked up how to properly shampoo and wash my hair, and have spend multiple times over an hour in the shower just trying to wash it out. i have no idea what i'm doing wrong and it's honestly so frustrating coming out of the shower and feeling th product still in my hair. even if i go in after it doesn't work. and i just don't think staying longer in the shower makes sense, since i know so many people with longer hair who take a quarter of the time and their hair seems fine. i also don't think the water is the problem bc i have roommates and they don't have that problem.
I'm just so confused, especially because it goes away for a few months even though i have not done something strikingly different and comes back again. That may sound contradictary but the hair routine itself doesn't change if the problem is there or not .I also tried rinsing it out with apple cider but then the cider also got stuck in my head.

I'm desperate for advice and help because - as ridicilous as it may sound - it affects my mood immensely bc i don't feel good with the hair and i don't know what to do.

So if anyone has encountered the same problem or knows something that could i help, i would appreciate it!