Protonmail will not open until another browser pops up over it which I have to close

I’m really at the end of my rope with this browswer. Overall it works OK however whenever I go to open my email (protonmail) another browser opens over it which I believe is the Tor Browser. This only happens after I put my password in. I have to close the tor browser to get to my email. I’m going to do that about 3 more times and I’m uninstalling. It’s turned checking emails into a pain in the ass and I’ve had it. I saw one threat discussing this and of course the suggestion was to go to extensions and disable forwarding something. Of course the outline of what was described doesn’t exist and the options being described don’t exist where they alleged to be found which is what I find to be the case 99% of the time with online forums. If anyone has any suggestions I would love to hear it because it’s a dealbreaker and if I have to learn to write computer code to fix it it’s a dealbreaker.