Why is third monitor always mirroring one of my other two in macOS?
For MacBooks, they only could extend one monitor. Other monitors only could mirror it. Because Macbooks' thunderbolt 3 port uses the Single-Stream Tree, it is a bug for macOS.
Solutions:
1. You need more thunderbolt 3 ports to help you extend two or three external monitors.
2. Work with UtechSmart USB C Dock/Docking Station comes with DisplayLink chip, then you just need to cancel the mirror display and can get the extend different displays.
Solutions:
1. You need more thunderbolt 3 ports to help you extend two or three external monitors.
2. Work with UtechSmart USB C Dock/Docking Station comes with DisplayLink chip, then you just need to cancel the mirror display and can get the extend different displays.
