If you are looking for "How to set up User-ID in Google Analytics", you may refer at here.
If you want more detailed analytics of the store, We recommend you to use Google Analytics. Please refer to this link for more information.
Sign in to your Google Account and visit the Google Analytics Page. Since you have never set up Google Analytics before, you'll be asked to sign up for one.
Fill in the details of your shop in the new page that shows up.
Note: Website URL must be your shop's custom domain URL.
Pick your desired data sharing settings then click "Get Tracking ID".
Change the Country/Region to your desired location then click "I Accept".
In the following page, copy the tracking ID as shown in the picture:
Go back to your shop admin panel. Go into tracker settings and choose "Google Analytics".
Just paste the tracking code in the input box below and you're all set up!
If you want even more advanced e-commerce analytics information, you can follow this tutorial to activate GA's e-commerce function. Please note that this advanced function is for basic plan/advanced plan/premium plan users only.