I hope this is the right topic. I’m trying to learn to use the app correctly now that I know what all of this is(after 7 years). First, can things be edited? Second, when I choose class from one of these little drawings/emoji type things below it changes what I chose as what I think it is. I don’t even know how to explain this. I am not a scholar and some of this is over my head. Ex: I originally chose turkey tail and tried to edit it by class and chose the little mushroom and it changed it to fungi/lichen. Apparently I had the wrong topic title because as I was typing it said it was being edited in another window and that threw me.
I only use the web version, but I think you don’t need to choose one of the icons unless that’s all you know.
The system knows that Turkey Tail is a type of fungi, so if you just identify your observation as Turkey Tail, it automatically gets put in the class fungi, and comes up if someone searches for all fungi. That’s certainly how it works on the website.
I can’t imagine the app is creating observations that work differently than ones made from a webpage, so surely OP’s Turkey Tail Mushroom observation would show up to someone searching for fungi in general like we’d expect.
Yes, in both app and online, one does not need to select the “Iconic Taxon.” (Which means the little carton drawings of different major groups.) If you have selected it and want to add a finer ID than just ‘fungus’ you still can.
More generally, to understand how the site works, how to make an observation, etc. you might consider browsing the help pages: https://inaturalist.freshdesk.com/en/support/solutions/folders/151000552105
Yes. Everything can be edited. Hit the pencil (“edit”) icon at upper right and go for it.

