If i stand up too fast, my vision goes dark and i feel like fainting. but i want to know is there any way to fix this?

Pre-syncope: Seems like sudden postural chnage is dropping your blood pressure and causing above symptoms. Hence you need to chnage your psoture gradually, thigh high stockings are helpful, if you are taking BP medications- dose should be decreased, liberal intacks of salt, plenty of oral fluids, avoid too much diuretics, avoid extreme climatic conditions. Consult your physician for further work up.