Restore my browser to what it was yesterday

Hi

Have you recently updated Firefox?

Yes but I didn't want to.

How do I restore Firefox to previous session?

Please restore my browser to previous session!

Hi

Has something gone wrong? Is something missing?

My previous browser let me open several web sites on top. Upgrade removed that convenience. How do I get the previous browser back?

What do you mean by "open several websites on top"?

I could open several web sites and they would line up on top of the address bar and I could click back and forth especially while trading on the market.

If someone can tell me how to get Firefox back to the previous version, I won't need to explain.

It sounds like you may have enabled vertical tabs. This support article should help you to turn them off again:

https://support.mozilla.org/en-US/kb/use-sidebar-access-tools-and-vertical-tabs#w_turn-on-vertical-tabs