LFE mode and crossover

Hi! I have Nad M10 with passive speakers LR, Bluesound wireless sL and sR and Pulse sub+. When as home theater group can i use the sub just as LFE sub or do i have to set crossover to my LR speakers also in the same time selecting to use the sub? (select 1 or 2 subwoofers) I want to use it only for effects watching as my LR would playback all the way from 20hz all the music and etc.. And can i somehow do different groups for home theater and just stereo pair at the same time in blueos app? It is frustrating to build then all over again every time. Thank you!