Everything here is play: tap, drag, carry and launch, and time answers. A clock that moves fast ticks slower. A clock that sits higher ticks faster. Satellites are both fast and high - up there, faster wins, about 38 millionths of a second a day. Map makers wind satellite clocks back before launch so your pin stays where you are. That bendiness of time is Einstein's relativity.
Tick gaps on screen are stretched so you can see them; the real ones are millionths of a second. Heights and speeds are playful, not to scale.
GPS and Relativity (Ohio State University)
Ashby, Relativity in the Global Positioning System (Living Reviews in Relativity)