I've been "fumbling " around setting for 10 min , still no idea how to do it .
Ty for the link on the guide StarMaker
EDIT : How to actually upgrade your Artifact
Step 1 : Click on your profile
Step 2 : Click on Artifact Presentation room
Step 3 : Find your artifact at the bottom of the page and click on it . Should be under Tech .
Step 4 You should see two options : Equip and Upgrade . Click on upgrade and depending on how much fragments you have upgrade it .
That should be it , at least it was in my case .