Photoshop Elements 12 to PE 2018 migration

I am being forced to migrate Apple Operating Systems from Yosemite to High Sierra.  This is having the domino effect of forcing me to migrate from PE12 (on Yosemite) to PE 2018 (on High Sierra).  I've searched on the forum but have not found a step-by-step guide on successfully perform these upgrades.  I'm not very technical and would much appreciate some guidance.  - I'll be staying on the same Macbook. 

Someone suggested that I shouldn't have a problem: That if I start with a clean Catalog (PE12).  Migrate my operating system.  Install PE2018 (I have on-order the box CD set of Photoshop and Premier Element).  Then all I have to do is open PE 2018 for everything to show up cleanly.  Somehow this sounds too easy/simplistic; I've had to re-tag too many photos in the past.  So I'm asking for help ahead of time. 

Thank you in advance, Amy