The default setting is probably showing the menu, up to a duration of some seconds, so that you can choose other OS (e.g. windows as dual boot). Then you probably need to edit a text file and run Update-Grube. Here’s an example set of instructions doing the exact opposite (turning off the hiding); hope it helps… https://askubuntu.com/a/1187104
I didn’t change the config at all, it’s default.
The default setting is probably showing the menu, up to a duration of some seconds, so that you can choose other OS (e.g. windows as dual boot). Then you probably need to edit a text file and run Update-Grube. Here’s an example set of instructions doing the exact opposite (turning off the hiding); hope it helps… https://askubuntu.com/a/1187104