Can't find High Sierra option for update
I am using Yosemite and want to update to High Sierra but the only option I get is to go to Mojave. I have verified all the qualifications for update and there is no reason I shouldn't be able to update. I just can't get the option. When I click on the updates tab, all I get are apps, no operating systems.
iMac, Mac OS X (10.7.4)