Windows – How to get Windows 10 to stop asking me to update the file associations

• Run / gpedit.msc (edit group policy)
• locate and expand Computer Configuration / Administrative Templates / Windows Components now click on File Explorer
• on the right panel, double click on "Do not show the 'new application installed' notification" and set it to "Enabled"

This policy removes the end-user notification for new application associations. These associations are based on file types (e.g. *.txt) or protocols (e.g. http:)

If this group policy is enabled, no notifications will be shown. If the group policy is not configured or disabled, notifications will be shown to the end user if a new application has been installed that can handle the file type or protocol association that was invoked.

You should be able to do the following

1. Open File Explorer (right click Start -> File Explorer)
2. Find the file you want to associate
3. Right click the file and select Properties
4. In this window click Opens With
5. Select the program you want to open this file

Note that this dialog box tries to guess what program to use. Sometimes it's very wrong. I had to scroll down, select More Apps, and then scroll down again and click Look for another app on this PC before it gave me a file explorer to look for files.