Role combobox (form) default value

Hi !
I have a few registration forms depending of the role, the user wants to have. Each form has specific custom fields.

Regarding the profile page, I made one with a “Profile form” containing all the fields with conditional visibility relative to a role combobox value.
Now, I would like this combobox default value to be set to the current user’s role (and not editable) so the custom fields are displayed accordingly.

Can anyone helps me regarding this default value please ?

Thanks for your help.
Toshi