How do I update MacOS High Sierra 10.13.6
I have a 2011 iMac running macOS High Sierra 10.13.6
I need to download office apps for my kids to do their home schooling but App Store says I need os 10.14 or later to download office apps.
There are no updates available from App Store to my os so what can I do?
iMac 21.5″, macOS 10.13