I am not able to create a backup and to manage it.
I am not a web developer. I’m afraid that by updating the theme something starts to fail.
Thank you @threadi
Yes, you understood perfectly, I don’t see in the editor when you highlight text.
No, I didn’t install any updates or plug-ins, at least to my knowledge.
How do you access the theme adjustments and in particular those of the highlighting text?
I point out that: inside the posts EDITOR the text selection is not showing anymore.