Tryina figure out how to cast. I have to assign a channel?

You can post in the apesociety channel so that everyone who follows that channel can see! (I.e all apes)

You don’t have to but to get more views it’s always good to post in a channel.

Pencil looking thing bottom right side of screen on phone

Yes, you need to assign a channel for casting. Check your device's settings to ensure it's properly connected to the desired channel. Make sure both devices are on the same Wi-Fi network for a smooth casting experience.