How would i be able to update my apple mac?

[Joee123]

Recently, I have bought a refurbished 2018 Apple Mac but the update doesn't seem to be working.

How would I be able to fix this problem?

 

[mj_]

By defining what exactly you mean by "doesn't seem to be working" and by specifying what update exactly you are talking about.

And just FYI: there is no 2018 iMac. There's a 2017 iMac and a 2019 iMac but no iMac in-between those two.