Default home screen is the page you see on the home screen when pressing the home button or rebooting your phone. To change default home screen on HTC 10, do the following simple steps:
1. Press the home button to make sure you are on the home screen
2. Press and hold your finger on an empty spot in the home screen to open the Personalize settings
3. Select the "Manage Home Screen Pages" option from the bottom of the list
4. Now you can freely swipe left/right to move between home pages
5. Swipe to the page you'd want to set as the default home screen page on HTC 10 and hit the SET AS HOME button on the bottom left
6. You are all DONE.