Help please. My extensions on my downloaded designs on the computer 10 are jef as should be, however they no longer open.  It says on the computer - Digitizer stitch file??  My design files using my digitizer  dongle seem to be working  as before windows 10 ugh! Thank you

This is a regular occurrence with Windows of all flavors. Whatever program is installed LAST becomes the default for all the file types it supports. Here are some pages that should help you resolve it:

https://support.microsoft.com/en-us/windows/change-default-programs-in-windows-10-e5d82cad-17d1-c53b-3505-f10a32e1894d

https://www.pcmag.com/how-to/how-to-customize-your-default-apps-in-windows-and-macos

https://www.bleepingcomputer.com/news/microsoft/windows-10-making-it-easier-to-manage-default-file-associations/