How can I get shorts white again.

If you have some place you can hang them in the sun that will help . Maybe across a chair or deck railings . Good luck

https://www.youtube.com/watch?v=8nc8SXYlpZM

Bleach will ruin the fibers of the fabric and turn them yellow or a dingy gray. Try a soak overnight in baking soda. Here are some other options for you!

https://www.wikihow.com/Get-White-Clothes-White-Again

https://www.thespruce.com/how-to-keep-white-clothes-white-2146392

https://housekeeping.wonderhowto.com/how-to/10-ways-whiten-clothes-without-using-any-bleach-0162473/

I rely on Oxiclean for this sort of thing. I had red wine spilled on white stretch pants. The dry cleaner ran them through twice but there was still a shadow. I followed the directions Oxiclean gives and boiled a big canning jar size pot of water on the stove —with recommended amount of powder in water. I put the pants in and sloshed them around until I was sure they were soaked. Then I stopped by to slosh them around every once in a while. I left them overnight before dumping them out and fInding they were perfectly white— no shadow. The pants weren’t hurt in any way.

bleach was not the best choice......soak them over night in baking soda

Rit Dye makes a color remover...that is easy use!

My bet is on Oxyclean! It has pulled us through many of these events with great results. Every now and then the white laundry some how gets a red sock gets in there, either by accident (grabbing a big load) or it was left from a previous load of darks. You guessed it, the white load is now pinkish. Oxyclean is put in the same load minus the red sock and let it soak, occasionally giving the load some tumble time in the washer, stop it again, repeat until you think it has tumbled and soaked enough. I have even let it soak overnight. When you have finished the wash cycle, hang the clothes outside to line dry.

Try the stuff to remove rust for laundry, it worked for me.