try greased lightning cleaner,scrub,rinse and clean with vinegar and water mix
Use liquid fabric softener
First get it clean. Then use RainX car wax on it to repel water and keep it clean!
I use vinegar & water (50/50 mix in a spray bottle) with a few drops of Dawn to get rid of any and all water spots. Simple spray it on, leave it for a short time to let it work, spray on more if needed. Wipe down with a soft, preferably microfiber, cloth. Your shower door should shine. If it's extreme, you can first make a paste of baking soda & water, let that sit, then proceed with the vinegar/water process. I hope this helps. Wishing you the best.
Try vinegar and after the spots are gone wipe shower with mineral or baby oil.