I want to try the 2.4 but I’m not sure how. Do I select 2.4  and a channel with with the most signal before flight? Ty

I typically leave it on 2.4.  So yes, in the settings, select 2.4 and you can let the channel default to the first one or change it.  

If you select 2.4 the AC and RC will choose the best channel to operate.

Sounds good thankyou.

The green lines indicate interference so chose the one with the least or the lowest green line.

Ok ty. I will try it out next time I go flying.

your phone also must support 2.4 ghz and 5ghz

Im using a iPhone 6s+.It should be ok..

Spark supports to switch between 2.4 GHz and 5.8 GHz. Happy flying!