I use Opera as browser, and opera mail for my pop3 email.
After Mrs W had used the PC, and complained that Alfie the brainless cat had stomped all over the keyboard, Opera had lost its "Speed dial" settings (sort of quick graphical bookmarks), but had saved them under another name, which I managed to retrieve after an hour of jibbling, but the lingering annoyance is that now every single bloody time I start Opera, the windows settings thing opens up, asking me to choose default programs for various things. Well, I don't want to change them, they are correct!
Any clues as to how I stop this intensely annoying behaviour? There is a serious limitation in that Win10 settings thing, as it is incapable of allowing me to look for other programs than those in its little list for each activity. For email it suggests "mail" which I have discovered means windows mail, not opera mail, and other things I don't want, but not Opera mail. However it does offer me Opera mail for some other activity, I forget what, which is nothing whatever to do with emails... I personally don;t care if it doesn't have the correct email prog, as the only time its ever needed is when clicking on a "mailto" link, and I'm perfectly capable of cutting and pasting that into opera mail anyway. its a rare occurrence anyway.
So, any clues as to how to stop it hassling me, and just letting me use my PC without interference? I'm actually suspicious this was a surreptitious Window update, nothing to do with blunderpuss.