Why are buttons icons so small in the Settings window?
This is probably because you are using QAP on an HDPI-devices (like Surface Book). On these screens, icons on QAP Settings window may not scale properly. See this example: on the left, the Settings window on a standard desktop PC and, on the right, the same window on a Surface Book.
The scaling effect also impacts icon sizes in QAP popup menu. You could compensate this scaling by changing menu icons size in Options but this would not fix the buttons icon size in the Settings window.
Thanks to QAP user Jörg Giencke, you can use this tip from brianapps (the developer of Sizer 4.0): right-click the Quick Access Popup executable icon in Windows Explorer, select Properties, then Comptability, check Override high DPI scaling behavior and select System from the dropdown list. This goes for Windows 10 Creators Update (and other Windows 10 version on HDPI-devices?). After that everything displays just fine on Surface and other HDPI devices.
It is recommended to reboot the computer in order to enforce the change and clear out older settings or window displays.