Hi. Hope someone can help. I’ve always had fixed bridge or satellite trem guitars but recently got one with a floating bridge, an Ibanez RG320. It plays great but I wanted to bring the action down a bit, so I slackened the strings and adjusted the screws at the front of the bridge. Also the bridge was pretty far from parallel to the body, so I took the backplate off and adjusted the screws attached to the springs too. I had it playing just like I wanted it, but the next day the action had gone back up. I’ve repeated this process a few times now, and each time I get the guitar out the next day, the action has got higher!!! Any ideas why this is happening?
OK thanks, thought it might be defective hardware rather than anything I'm doing wrong...
I am not sure about the RG320, but some other guitars with Floyd Rose type floating bridges just use screws in the body wood for the two pivot screws (the two front screws). There is considerable tension, of course, on the strings and therefore the bridge. Also, if the guitar is used or a "demo", the two pivot screws may have been "adjusted" so much that the wood has fatigued. A simple, but time consuming fix, requires total removal of the strings & bridge pivot screws so steel wool can be inserted into the stripped-out holes in the wood.

IF the two pivot screws are into threaded, metal inserts, then either the screws or the inserts may be partially stripped. If it is the screws, new ones will be needed: and the same removal of the strings and bridge is required. If it is the inserts, I suggest taking the guitar to a very experienced luthier - someone who knows how to remove and replace them without damaging the wood of the guitar.
i would take a few minutes and read through this: http://www.ibanezrules.com/tech/setup/

IMO it has some of the best tremolo setup information out there.