I bought a used hss squier standard strat and I noticed that there is significant buzzing that goes away when touching any metal part on the guitar. It only happens when the pickup selector is in the first position or the 5th (the humbucker?!) The other three positions are fine. Is this a big problem or will I be able to fix it by myself?
You have a bad ground (or earth) connection in your guitar wiring. This can be caused by a "cold solder" joint where not enough heat was applied, or a loose or broken ground wire. To fix it requires using a soldering iron and identifying the bad connection. In some cases it is easier to retouch all the solder connections than trying to find the one cold joint.