[UX] Make the color settings on the main `Preferences` tab more obvious

[Korb]

Problem / Use Case

If you're unfamiliar with this app, setting it up is currently quite a complex task. Although there is no reason why such simple things, which are embedded in its settings, should be executed so mysteriously. In particular, the color settings block on the tab... no, it's not a tab, but the top level of the app's settings, as odd as it may seem from a logical standpoint of structure and navigation.

Be that as it may, what exactly does the user see:

• A button labeled Day. This is likely the daytime color theme settings button.
• A button labeled Night. This is likely the nighttime color theme settings button.
• A button with an image of settings. These are likely global settings that aren't in either the daytime or nighttime theme settings, but apply to both.
• Eight mysterious buttons:
  • Button 1
  • Button 2
  • Button 3
  • An unlabeled button with a background image. This is likely the wallpaper selection for the daytime theme, but why is it located below the nighttime theme button, and why isn't it in the daytime theme settings?
  • Button A
  • Button B
  • Button C
  • An unlabeled button with a background image. This is likely the wallpaper selection for the nighttime theme. But that's not certain. It might be a setting of the 10th color theme. But if the app allows you to customize ten color themes, how do you switch between them?

Clicking the button with the settings icon displays a Configure dialog (configure what exactly?) with 12 unlabeled color-code-links. There's some connection with the six buttons in the second row, but it's unclear why their settings aren't in the dialogs that appear when clicking the six buttons.

In the next dialog that appears when you click on the color-code-links, it is not always possible to change the color, even if the user seems to have the option to change it. The color isn't saved.

Current Workaround

Don't use app settings, just use the default settings, which aren't suitable for all users.

Proposed Solution

I can't offer a good solution because I still haven't fully understood the logic behind these 11 buttons and two levels of nested dialogs.

At least: add a question mark icon (❔) that explains in detail what each button or link does and the logic behind it.

Additional Context

Related to #668 (total usability issue)