Follow steps below to save customers segment:
Log in to the app.
Go to Customer Insights from sidebar navigation menu.
Click Add Filter than choose customer filtering condition accordingly and Run Filter. You can choose more than one filters at a time.
After filtering, a button Save Segment will appear.
Click button Save Segment, give a name to it and save.
View your saved segment in the list of predefined segments.
Also, you can have a glimpse at a video below which will guide you for saving predefined customer segments.