Text that I typed changes when I hit enter in a text document?

When I hit enter to go to a new line in a text document the font size changes, and any bold/italics/underlining I had goes away. I have to click “undo actions” to revert it back to what I typed. How do I remedy this?

I think I found my answer. If I hit “Shift/Enter”, instead of just “Enter”, when going to the next line, the font size/bold/underline, etc stays just as I typed it. I do not have to hit the “Undo Actions” icon.

If there is a way to change this in LibreOffice, so I do not need to remember to hit the “Shift” key each time I hit “Enter” to go to a new line, please be so kind as to advise me. Thank you.

Caution! Enter is not the same as Shift+Enter. The former closes the current paragraph and opens a new one. The latter only inserts a newline in the present paragraph; this may not be what you intended (in particular, it has “strange” but so designed effect on justification).

Does your issue occurs both before and after Enter? Have you used specific paragraph and character styles or only manual formatting?