Table of Contents Issue

Hello again,
I think this time you have resolved my issue. However, I would like to explain the manipulation that allowed me to retrieve a coherent table of contents, displaying levels 1 to 3.
Without needing to change files, the problem stemmed from a residual style "title 1" (with a lowercase t) that I had created as a test style for level 1 headings. This style was appearing on my body text despite my requests to change it to "memory style." So I deleted the residual style and everything fell back into place. My table of contents is coherent, and my formatting styles are working according to the rules of the art (which I wasn't too far off from, after all).
Thank you again, Marina, I will keep your address safely with a note "Word assistance" next to it.

First of all, thank you for your help, which partly solves my problems. Indeed, the "memoir style" text style no longer affects heading level 2 but "body text," yet the body text is still displayed in the table of contents despite my request to display levels 1 to 3. The "copy" "paste" attempt in a new Word document did not change this fact. I believe I have located the source of the problem: in the "styles and formatting" tab (the tab that displays the list of the last used styles), the "formatting of the selected text" does not vary, whereas it varies in the formatting toolbar.

As for the page numbering, I have already read the rules of thumb you referred to, and from my understanding, my pagination is the only possible one for my case, which is to create a partial numbering for each heading level 1 (which corresponds to the sections) of my document, and thus a reset of the page counter for each section, with a manual input of the total number of pages in the section. If there is another way to paginate, I thank you in advance for sharing it with me.