To address the issue of being unable to add an extra line in Ball Sort Puzzle at level 10937, follow these steps:

1. Confirm the Level: You're currently on level 10937. Ensure that you are indeed on this level by reviewing your game state.

2. Check Game Settings: Access the game settings or preferences within Ball Sort Puzzle. Sometimes, there are options related to gameplay that may affect the ability to add lines or modify the play area.

3. Restart App: Close the app completely and restart it. This can resolve minor software glitches that could be causing this limitation.

4. Update the Game: Make sure that your game is updated to the latest version. Go to the Google Play Store, search for Ball Sort Puzzle, and see if there’s an update available. Install any available updates.

5. Clear Cache: If the problem persists, clear the app's cache. Go to your device's settings, then to "Apps", find Ball Sort Puzzle, tap on it, and select "Storage." From there, choose "Clear Cache."

6. Check for External Help: Look for online guides or gameplay videos specifically related to level 10937. Helpful resources might provide strategies or tips that assist in overcoming any obstacles. You can check out this YouTube link that discusses solutions for level 10937 - learn more.

7. Interact with the Community: If you’re still stuck, consider reaching out to other players. Forums like Reddit or game-specific communities can provide additional insights or solutions that may not be widely known.

8. Reinstall the Game: If nothing else works, you may need to uninstall and reinstall the game. This should rectify any corrupted files or significant issues caused by updates or cache problems.

9. Contact Support: If you continue to face difficulties, contacting the game’s customer support might be beneficial. They can provide assistance or clarify whether the ability to add lines is disabled on that specific level due to game design.

Applying these steps should help you regain full functionality in the game and successfully navigate level 10937.