
Let's assume that afterwards I open another (still existing) document
- either bei clicking on its title in the tree
- or by clicking on a link to it in Document 1
and then I return to Document 1 (typically by clicking on the button "Go back to" in the tool bar, or by clicking on its title in the tree).
After returning, this document usually (I am not sure if it happens always) has a small left and first indent - or at least such an indent is shown by the marker which has now moved a little bit to the right:

As you can see, the difference is very small, but it exists. I do not know if it has a (marginal) effect on the formatting of the document.
And from now on, this (indication of a) slight indent remains, either for other already existing documents opened either for new ones created afterwards:

In order to restore the correct position, of course you can move the marker manually back to the left end of the ruler. (Strangely, after such a procedure the marker remains there, even after opening again another document and going back to the first one.) I already made this manual shift of the marker for a lot of documents but of course this is something quite cumbersome ...