2 displays problems

It sounds like you are experiencing some issues with using dual displays on your Asrock H470 Mini-PC running Windows 10 64-bit. I'll try to address your questions:
1. To ensure that your primary HDMI display stays as the primary display after expanding the view, you can try adjusting the display settings in Windows. Here's how you can do it:
a. Right-click on your desktop and select "Display settings" from the context menu.
b. In the Display settings window, scroll down to the "Multiple displays" section.
c. Select the display that you want to be the primary display (in this case, the HDMI display).
d. Scroll down to the "Multiple displays" section and check the box next to "Make this my main display."
e. Click on the "Apply" button to save the changes.
By setting the HDMI display as the main display, it should remain as the primary display even after expanding the view to both displays.
2. Regarding the issue with the mouse cursor not easily moving between the two displays, there could be a few reasons for this. Here are a couple of troubleshooting steps you can try:
a. Make sure that the display arrangement is set correctly in the display settings. In the same "Display settings" window mentioned earlier, you should see a visual representation of the two displays. You can click and drag the displays in the diagram to rearrange their positions. Make sure that the VGA display is positioned next to the HDMI display to allow easy mouse movement between them.
b. Check if there are any display drivers or Windows updates available for your Asrock H470 Mini-PC. Updating the drivers and Windows can sometimes resolve issues with dual displays and improve compatibility. You can visit the manufacturer's website or use Windows Update to check for updates.
If these steps don't resolve the issue, it's possible that there may be a hardware compatibility limitation or an issue specific to your setup. In that case, you could try reaching out to Asrock support or seeking assistance from a computer technician who can troubleshoot the issue further.
I hope this helps! Let me know if you have any further questions.