I changed some of the mobile toolbar settings after clicking the gear icon a long time ago and now the gear icon has disappeared so I cannot make any further changes to the mobile toolbar.
I tried reinstalling the app and deleting app storage data but have a feeling these settings are synced. Is this a bug perhaps?
Maybe a way out: use the web browser to go to dynalist.io and login. If you make the browser very narrow, it will go to mobile mode and maybe you can find the icon bar settings.