Is it possible to upgrade my humbucker lp so when I press down the volume pots, they go from single to humb and the other way around? Also what should I have to buy to do that if possible and how much does it cost?
Thanks in advance.
If your pickups are using 4 conductor wire then it is possible. If your pickups are using braided 2 conductor wire then you would have to modify or replace the pickups which is either going to be tricky, or expensive.

The push pull pot you would need only costs between 5 and 10 quid so if you can do the work yourself then it's cheap and easy. Diagrams on how to do it can be found on the seymour duncan website.
Not taking any online orders.