How many hours of the day should i wear my retainer if i have a crossbite and i have to wear it to push some teeth forward?

See orthodontist: Retainers are made once your orthodontics has been completed and your teeth are in the position where you want them to stay. Most ties you would start by wearing them full time. A retainer would not move your teeth. It would take active orthodontic treatment to do this. So call your orthodontist and they can advise you on what to do now.

Depends on situation: Active tooth movement with removable appliances usually requires 22 hour per day wear. This obviously depends on the specific condition and needed tooth movement. Please call your dentist to discuss your specific case.

24: 25 would be even better. Go looking for reasons to wear your appliance rather than excuses to take it out. Removable appliances, including clear aligners, only work when worn as opposed to braces that work all the time. Please see a qualified orthodontic specialist to discuss the best way to resolve your malocclusion.