Change Edge/Bing to Firefox/Google as default when using Win key, pls?

I'm having some issues with Microsoft Edge. Yesterday it was fine, but today the page with top sites is broken. Tried reinstalling Microsoft Edge, but that didn't help. I somehow found out what's causing it and it's setting default search engine...

Windows 10 Microsoft Edge opens in Bing. I would like it to open EVERY TIME using Google. I went to More Options, Open With, A Specific Page Of Pages shows Custom with Google below that. I then went to More Options, Settings, Advanced Settings,...

Changing search in settings ADVANCED when you click on the add new all lines are greyed out .What to do ,or what causes that?I DO Not like Bing

how do i change my edge to google is my question.Also i did the upgrade but it also keep my old operating system and even though im administrator it wont allow me to remove it should i do a fresh install.