Using "External FX & Send & Return" + "PATCH BUS TO A1 ASIO OUTPUTS" + "PATCH COMPOSITE" Understanding when to use them

[AKSKMY]

Hi all,

I would like to know how each of these functions work and in what scenario would each be used effectively? These are the only functions which I can seem to get my head wrap around as of now.

I'm currently using the Focusrite Scarlett 2i2 GEN 3 , as such which function would I be able to use? I have also managed to use the general function of using Output A1 as ASIO inputs to strip as per default.

Thanks!