Bike trying to jumps gears when I stand
I presume you mean the rear derailleur jumps to a higher (harder to pedal) gear when you stand up to pedal hard, right?   This is a common rear derailleur problem, happens only  under high chain tensions, and more likely with inexpensive or worn rear derailleurs.  It shouldn't do that, as it can be dangerous to the rider.  So you need to get it fixed.    Your rear derailleur either needs an adjustment, or a replacement spring,  or you need to replace it with a new or better one.