I am assuming that you mean using the Sugden IR remote? This is very odd as remote commands have a finite code length and just releasing the remote command button should not revert to the previous status quo. That would normally require a further command. Would you firstly kindly check that your description of the issue is accurate?
Edit and NB: the display when switched off will switch on again for a brief period when other control options are selected. So of if you are selecting volume on the Sugden and that is erroneously recognised as a valid code for a Bartok function the display will switch on for as long as you keep your finger on the button if the remote then sends repeated commands. I would select the control lock option once your control options have been selected to your satisfaction as this should stop the issue if the Bartok function being selected in error is subject to the lock ( see manual).