I've experienced quite a lot of confusion trying to understand the Xcode User Interface. It can be frustrating to learn a new tool. And I've always thought that Apple did a great job putting people first in their design process.

Here's my current - EXCEPTION - unproving the rule...

I've never been able to figure out where to go to find the Editor gutter view controls. So I stopped writing code for a while and explored the Xcode UI. And the weirdest thing poped out. The left gutter view controls are in Preference popup. The right gutter view controls are in the Editor menu selections.

So if one is looking to change views typically on the left:

Preferences Popup…

Preferences > Text Editing > Display > Show: ☑️ Line numbers

Preferences > Text Editing > Display > Show: ☑️ Code Folding Ribbon

Preferences > Source Control > General > Text Editing: ☑️ Show Source Control changes

The Minimap - shows a very small font overview of the whole file and a subselection of your current page's view within the overall file.
Authors - is a source control attribution - who last touched the line... good for blaming your co-teammates. I don't suggest this behavior.
Code Coverage - does your unit test actually touch a line when it runs... good for finding the misses - but just because it ran once - does NOT mean it is right nor correct.

Why are these on the Editor menu - but the views above (lefthand of the editor view) are in Preferences popup? A UI inconsistency... leading to multiple mental models for the average person which naturally leads to confusion.