When I double-click on a desktop icon for a file with an .ods extension, it opens in gedit rather than LibreOffice. I have to resort to the Open With right-click menu to get into LibreOffice. Can this be fixed?
Please make sure you have LibreOffice installed. If you have it installed, when you right click on the file, the dropdown menu should say "Open with LibreOffice Calc". If you don't see the option, click on "Open with other application". In recommended applications list, if you don't find it, click on "View all applications". Click on the appropriate application and click select.
If you have multiple distribution of LibreOffice installed, you might have library conflicts between different versions. To reinstall LibreOffice, remove installations of LibreOffice:
sudo apt-get remove libreoffice-core
If you also want to remove LibreOffice configuration files, use the purge switch:
sudo apt-get remove --purge libreoffice-core
Now to install LibreOffice, you can use official ppa:
sudo add-apt-repository ppa:libreoffice/ppa
Update your apt repository
sudo apt update
sudo apt install libreoffice
Now it should open with LibreOffice.