Sonya updated to Windows 10, and now she can't print from Yahoo Mail. Leo says that there seems to be a disconnect with the web browser. It could be that the Yahoo print manager doesn't support the Edge browser. Microsoft shipped Windows 10 with two browsers -- Edge and Internet Explorer. The Blue 'E' is actually Edge now, and Leo says it was shipped prematurely to grab the back to school market for search.
A big update is coming in October that will likely have the "cooked" version of Edge, and it's capabilities will be improved. In the meantime, Sonya should try another browser like Google Chrome, or even Internet Explorer. Just click on the Start menu and start typing Internet Explorer to get to it. She should also try using the Edge print command. Click on the three dots and see if it's greyed out. If it is, then Edge doesn't print. Which means that feature isn't enabled yet.