Why you see the app logo in the menu bar
open Numbered Headings (the configuration pop-up appears)
settings are changed
apply button is pressed
The logo of the person who made the change shows in the menu bar (the exact same behavior as normal page publishing).
Enabling numbered headings on a page means that later edits to page content (and re-publishing) automatically triggers updating of heading numbers. These updates are attributed to the app and you will see the app logo in the menu bar.
Note that heading numbers are only updated when necessary. If you edit a page, make no change or a change that doesn’t affect heading numbers and re-publish, nothing happens.
Custom formatting applies to all heading levels
Numbered Headings does not allow setting different custom formats for each heading level (H1 - H6). This is by design. We feel that users want numbers like 1.a, regardless of whether the number is assigned to H2 or H3. Specifying different formats for each heading level adds complexity and can lead to extra work or mistakes.
You choose a custom format for each section of a heading number, and it is applied to all relevant heading levels. For example, if you choose to have the first subsections use Latin (and everything else is decimal), a document with the following heading structure will be numbered as shown:
As you can see, the first subsection would always be Latin, regardless of heading level.