Google Analytics reports show 2 metrics by default:
New Users = those are NOT returning users
Users = new users + returning users

However, if you want to show the number of RETURNING USERS in your reports, you can create a calculated metric, you can name it "returning users", then apply the formula (users - new users). After you creating a calculated metric, you can then use it in your reports. What is cool about this is that calculated metrics will incorporate past data!

source: I am a digital analytics specialist
( https://www.lucapennisi.com )