How to show toast/text on imagetarget

Hello!

I wanted to ask how can I show a toast or text to appear on camera screen itself and not on the top of imagetarget if a pointed the camera on a specific imagetarget. Like for example, I pointed the camera on imagetarget1 then it will show the usual 3DModel I specified for it then when I point the camera or imagetarget2 or any other imagetarget it will show the toast/text "Error" on the camera screen itself and not on the top of imagetarget.