There are 3 main layers of formatting in Writer, from deeper to shallower:
- paragraph style
- character style
- direct formatting
Every shallower (higher) layer overrides similar attributes. But every layer is independent from the others.
When you set a style (paragraph or character), it remains active until changed (either by a Next Style setting or a manual application). The same goes for direct formatting.
This means that a character style remains effective when you hit Enter to end a paragraph and start a new one. The same for direct formatting.
You didn’t tell how you enabled list numbering. I assume you either pressed a toolbar button (full direct formatting) or applied a list style (partial direct formatting). Since this numbering lives in the direct formatting layer, it remains active after Enter. But this type of direct formatting cannot be cleared with Ctl+M.
It is possible to shift list (or bullet) numbering into the paragraph style layer to make it disappear when you change style. This is done by changing paragraph style configuration in Outline & List tab where you associate a list style to this paragraph style.
You have noticed that all built-in List x (intended for bullets) and Numbering x (intended for numbers) styles do not show bullet nor number as shipped from the factory. You can associate your preferred list style to them.
If you do so, I have not sure if you won’t meet issue in the presently numbered items. As always, direct formatting is very sticky. My procedure to get rid of spurious numbering is to disable it (press Bksp at the very beginning of the item), apply Body Text (Ctl+0) and reapply my numbered paragraph style. After this stance, situation is back to normal.
REMARK
There are two schools regarding list numbering.
- full styling: you specialise paragraph styles to be automatically numbered; this is my preferred method, but some object that it implies more paragraph styles
- direct-format numbering: a list style is applied on any paragraph style; but you then bump into the general issues of direct formatting
In any case, avoid using Format>Bullets & Numbering or the equivalent toolbar button because it is unfortunate (personal opinion) compatibility device to mimic the badly designed feature in Word. It may not look so but you sooner or later meet big problems when you want to interleave separate lists.
PS: due to subtle differences, always mention OS name, exact LO version and save format. The latter is particularly important here because DOCX has no notion of list styles.
