Hello VolcanicMink,

Before be in Uv mode, set your viewport with the default settings (3 square/ 3d perspective on the left and 3d uv on top right/2D uv on bottom right)

Click in 3d perspective/ go in poly mode selection/ select all/ unwrap and you should see you UVs appearing in the 2 other windows

Select the 2 D UV port and press "space bar"

You should have your UV viewport open now.

Always in poly selection mode, select and move your UV

Press space bar again and you will be in the 3 viewport display mode.

Hope it helps

Best regards,