Thanks to
indexofrefraction and Klaus for the prompt and useful tips.
I've resolved and understood about the visibility of the VRSETUP button now.
About the second question, pherhaps I was unclear.
I'm trying to explain me better:using an Oculus Go, I wish to position a .png file (my logo) in order to have always the same orientation in relationship to the user eyes, also with if he moves the head around.
In other words I wish to have the words present in my logo always readable (I've attached a sample of what I need).
In desktop view I have correctly realized it defining:in webvr.xlm
<hotspot name="spot9" style="skin_hotspotstyle_logo" keep="true" ath="0" atv="90" depth="160" torigin="view" zorder="999" scale="1" />in vtourskin.xml
<style name="skin_hotspotstyle_logo" url="logo_tondo.png" edge="center" distorted="false"
tooltip=""
linkedscene=""
linkedscene_lookat=""
/>
But with Oculus Go the image still remain locked.
Since the "VR Setup" button works exactly how I wish, I suppose that in some parts I have to insert an expression like:
onloaded='renderloop( copy(ath,view.hlookat)',
I think it's too much for me... can I have a little help?