I created a file in LibreOffice, saved it in various formats with a password on the file. I used File => Save As => Save with Password. Does this protect my file only on my computer, or is the file now encrypted so I can safely email the document as well?
Saving file with password uses the file format to protect your data, so it’s independent of your system. Still, the level of protection depends on what the format supports; e.g., using DOC may give you lower protection than ODT.