Grub menù without double OS

I have Manjaro like unique operative system then I haven't to see the grub menu at boot. Is it correct?
I started to use this os one month ago, and it never was like now.
What can I do?
I'm not so expert about linux, I survive on it then you should tell me every minimal details.
Thank you!!

I don't quite understand your question, what I can guess so far:

  1. You expect to see grub menu at boot, but you didn't see it.
  2. You want to hide grub menu at boot.

Which one is your actual question? If none matches, try explaining in your native language and wait for someone capable of understanding to explain it better in english.

Re: double OS (entries?)
Uninstall grub-customizer and remove its stuff in /etc/grub.d

Re: haven't seen grub menu
If you want to see, press (keep tapping) 'esc' key at computer start.
If you want to make it permanent, search in this forum for 'menu_auto_hide'
ps: my method is better than the official method. Too long to write here. And not sure if that is what you want. [EDIT] - here