You will need to enable them to show in message user info under each field (custom user fields), and then enable the display of custom user fields under style properties -> message elements.
Edit each individual user field in the ACP, set them to show in user message info. Then under style properties, under message elements, set the display of custom profile fields.
Ok, you mean by "user field" members, moderators,...?
I'm sorry but I don't understand how to do that cause I have user groups but I have full rights as admin but I did not find how to put social networks images under my avatar "on topics"
Choose the field you want and then under General Options enable the display of the field in the message user info area. After that, as @Jeremy said, go to Style Properties > Message Elements and enable the display of custom user fields.