I have a game loop like this:

#The velocity of the object
velocity_x = 0.09
velocity_y = 0.03


#If the location of the object is over 5, bounce off.
if loc_x > 5:
    velocity_x = (velocity_x * -1)

if loc_y > 5:
    velocity_y = (velocity_y * -1)

#Every frame set the object's position to the old position plus the velocity
obj.setPosition([(loc_x + velocity_x),(loc_y + velocity_y),0])

Basically, my problem is that in the if loops, I change the variable from its original value to the inverse of its old value. But because I declare the variable's value at the beginning of the script, the velocity variables don't stay on what I change it to.

I need a way to change the variable's value permanently.

Thank you!