What version of blender is the turorial on ? I got 2 versions but can not get variety of colours automatically on my bone shapes. All same colour blue on blender 3.6.8 and 4.0.2 you have to change all the colours yourself which is a bit of a pain.
In 4.0 You can select multiple bones and then assign the bone color to all. Selected. I don’t remember if you have to hold alt down when you change the bone color or not.
In previous versions, you assigned the bones to bone groups and then select the color for the bone group. This is the same regardless of OS.
The colors themselves can be changed under themes section of the preferences editor.
Just add after data “.collections[##]” without the quotes and replace the ## with the number after the equal sign of index so index=7 would be 7. Then change layers to is_visible.