Logitech Easy switch between devices problem

[Nexus18]

I have the k780 keybord, which should work across different devices and it does but.... in order to switch between different devices, I have to hit the F1 or F2 key then switch the keyboard off to establish connection to said devices.

I'm wondering if this is because I am going from a built in bluetooth connection on the laptop to using a unifying logitech device connection on my desktop PC????