You are kind of between the rock and the hard place now, having already installed grub customizer.
Editing the gub configuration files manually now that grub customizer has taken over the configuration is very risky unless you know exactly what you are doing.
I think you may have rather painted yourself into a corner with the only sure way to straighten things out being a reinstall. My personal advice to you would be to not use Multi-booting if you are not capable of managing the boot problems that are inherent with installing multiple OS's on one computer.
Garuda ISO's do not come with multiple desktops or other Linux distros by default. If you choose this, you have created the problem. There is an old saying that I think applies here. Now that you have made your bed, you must lie in it.
Please edit your prior post to remove the picture and replace it with textual outputs, otherwise new users will assume pictures are the preferred method for posting textual outputs on our forum.