Hey, thank you for your reply!
So, I have disabled WP Super Cache plugin but unfortunately it did not help.
For the second part I am not sure which specific place you speak about :/
Customize -> Menu?
When I created this menu (with 4 horizontal lines) it was easy to find, but now I cannot find it anywhere to reverse the changes.
Could we maybe contact somehow in private? I will post a solution to this topic after that because I don’t even know how to attach a screen here
Kind regards!