The Lumia 535 did have quite a few screen sensitivity issues. Some of them were ironed out by a series of firmware updates, some of them had to be repaired due to a faulty screen. You could try the following options if you already haven't
1) Remove any screen protectors and see if it helps
2) Connect your phone to Lumia Software Recovery Tool and check if there is a Software Update available. This process would wipe your device data so make sure you have a backup. Another easy and recommended way is to check for software updates manually by connecting to a WiFi network and checking it from within the Windows Phone settings.
3) Try running some multi-touch tests after installing this app (https://forums.windowscentral.com/e...MultiTouch-Test%2F9NBLGGH09KVW&token=q8L-pPnd)
4) Perform a soft reset and see if it helps. Soft Reset instructions can be found here.