Depends on type. On mine there are two white threaded shafts the buttons slide on each one. first the round one then the halfmoon shape one that locks on to hold the round in place. The threaded screws/shafts are adjustable to vary height and adjusted so buttons are flush. However I do have one in shower room also which is different the shafts are ratchets push down to the correct level fit buttons. Now that's the problem which ones have you got. If you have a digital camera take a photo of the button assembly, the buttons and name of the toilet example: Twyford. take camera to plumbing/bathroom shop and show them they may be able to help better than forum as we can't see it. Always take pictures of what you are doing start during and end and that way if you get stuck on re-assembly you have photo reference enabling you to correct a mistake or know where the bit you got left over should have gone.
bb
February 2011