I have looked at previous posts about adjusting upvc doors but cannot see an answer to my query. My back door is catching slightly on the top catch and I think if the door was raised a couple of mm it would sort it. I believe by adjusting the allen screw under the hinges one can do this but there are 2 screws under each hinge. Do I adjust both or just one of them and which way do I turn them? Any advice would be welcome.