These helped me solve the problem:
How to easily remove old kernels in Ubuntu 20.04 LTS?
How do stop Ubuntu 20.04 from upgrading to the 5.8 hwe kernel?
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In Grub menu, the Ubuntu option launches kernel version 5.8, that doesn't work for me (black screen). In advanced options for Ubuntu I have kernel versions 5.4 that work properly.
I want to change the launch options of the Ubuntu option to launch a 5.4 version by default, so I don't need to enter Advanced options for Ubuntu, to choose a 5.4 version every time I boot. How do I do that?
Edit_1:
As you can see in Ubuntu parameters is the 5.8 version. I need somehow to change it to a 5.4 version that I can find in Advanced options for Ubuntu.
Ubuntu parameters from Grub2:
Edit_2
How can I change the code from 2 picture to use the "Ubuntu, with Linux 5.4.0-59-generic", instead of "Ubuntu, with Linux 5.8.0-36-generic"?
A potentialy bad solution:
Created a new menuentry "Ubuntu_2" using the script of the menuentry "Ubuntu", and replaced the "linux" and "initrd" lines with the code from "Ubuntu, with Linux 5.4.0-59-generic". It worked.