I do have Helvetica installed, and I do see it in the font selection menu, but what is displayed on screen (and printed) is Arial. This seems to only happen in LibreOffice, as if I open the same document in Word, it displays and prints properly as Helvetica.
Check your font substitution options:
If the Arial/Helvetica pairing is NOT there, then report it as a Bug.
If this helps then please tick the answer ()
I sometimes have a probem with fonts if my computer isn’t connected to the internet.
Arial is a font from Microsoft, and they might not be happy with you using it with LibreOffice.
If you’re on Windows and your copy came with Arial (which I believe is the case for every version of Windows since they introduced TrueType in 3.1), it’s definitely not an issue, as fonts have no licensing restrictions limiting their use to particular programs. To my knowledge, there was once even a ms-corefonts package for Linux.
This is a missing fonts problem.
Always remember that the font showing in the Writer font drop down select box is the font the document is asking for - it is NOT necessarily the font being used to create the display or print the document.
If the font being asked for is not installed Windows (or other OS) will silently, without telling the user, substitute an available and installed font.
The TestFonts add-on at hhttp://extensions.openoffice.org/en/project/testfonts is invaluable for finding fonts which the document is calling for, but which are not installed on the PC.
On Macs fonts are apparently installed in several different places.
You can see which fonts are installed by Start > Control panel > Fonts.