Hello
I understand that the “Extend” and “More” balloons popping up when your mouse goes to the edge of the screen can be annoying. Unfortunately, I couldn’t find a direct solution to disable these specific balloons. However, here are a couple of suggestions that might help:
Windows Shortcut: You can use the Windows shortcut to control display extension. Hold WIN and press P repeatedly to cycle through the following display options: Computer only, Duplicate, Extend, and Projector only. To enable an extended display quickly after turning on your second screen, hold WIN and press P until Extend is the highlighted option.
Monitor Arrangement: You could try adjusting the arrangement of your monitors in your display settings. For example, placing the other monitor to the left-hand corner in “arranging monitor” might prevent your mouse from running away.