The further a satellite is from the Earth, the weaker the pull of gravity on it. A weaker pull means less force is needed to keep it moving in a circle, so a lower speed is enough to stay in orbit.
A satellite in a higher orbit also has a longer path to travel for each lap. It moves more slowly and it has further to go, so its orbital period is longer.
Example: A satellite in low Earth orbit takes about 90 minutes to go round once. A geostationary satellite, much higher up, takes 24 hours.
This higher tier covers Higher Tier: Why a Higher Orbit Has a Longer Period within Orbits for GCSE Physics. Revise Orbits in Space Physics for GCSE Physics with 14 exam-style questions and 10 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 9 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Practice questions for Orbits
What is a protostar?
Explain why a main sequence star remains stable (in equilibrium) for billions of years.