Please be sure to turn the phone's screen off (press the power button (for Android) or swipe up with two fingers (for iPhone)) before you put the phone in your pocket. It will switch to black 'SmartLock' screen mode and reduce brightness to the lowest level. In this mode you can still scan the tags, but accidental inputs are blocked and screen does not use much power.
Here are two quick videos to demonstrate step-by-step for Android and iPhone:
NOTE: If this doesn't solve the issue, please report the problem about the round where you see incorrect/random entries.
To do this, while the round is active, tap the menu button in the upper left corner, select 'Report a Problem', select 'Golf Pad did not work correctly during this round', include a brief comment explaining what went wrong and send the report.