How to Change Folder Icon in mobile

Operating system

iOS

Joplin version

13.2.5

Sync target

Dropbox

Editor

Markdown Editor

What issue do you have?

I want to add/change folder icon in my mobile, but I couldn't find where to do it.
Is it only possible to change the folder icon in the desktop app?

It's only possible on the desktop app

Mine I set in the desktop app, and they show in my Android app just fine. I just checked and the 4 I set in my desktop app are showing in my Android. I am running Windows. So I suspect here is something missing in your IOS version.

And yes, there is no way to set them in the mobile version, at least not Android.