bbPress does not do this by default. Contact your theme author again if it is indeed your theme doing this.
You can do a quick test to see if it is your theme doing this. Switch to a default theme temporarily to see the default message bbPress has.
I have an idea of what the theme author might have done though. All I can say is for them to copy the default bbPress templates and start fresh and create their own bbPress styles and functionality.
Or I guess you can create a child theme and do the same thing.
If it is another plugin causing this, check that out.
You are right. I switched to Twenty Fifteen theme and it doesn’t have this problem.
I am asking about the theme author again. Can you give me a hint where to change this settings manually?
Any of the main bbPress settings are in Settings > Forums in the WordPress backend.
Does your forum look sort of like this?
http://support.aquagraphite.com/
@Robkk, yes, your forum have the same problem. Guest cannot see reply. There is no such settings in Settings->forums
Not my forum.
I think your theme author pretty much just took this and fused it with their theme.
https://github.com/syamilmj/Supportte
This theme (supportte) is really intended to be used as a theme for Envato authors that want a support forum also for their product.
The verification dialogue is there because the Aqua Verifier plugin is required for some instances of your bbPress forums. The plugin is to restrict access to only users who bought a product from you (best if you are an Envato theme author) and they need to input the purchase code of the product they purchased (from Envato) to have access to the forums.
https://github.com/syamilmj/Aqua-Verifier
There is no setting in bbPress that can modify this like I said, it is all in your theme and the Aqua Verifier plugin is required.
Link your theme author to this topic if you need to.