How to change colour settings in user profiles - Remote Desktop Services (RDS) in Windows Server 2012

Hi! I need help. I have Windows Server 2012 with HP Thin Clients. I use Remote Desktop Services (RDS). Recently, something wrong happened in the all user profiles. The background turned to black so there are lots of problems to recognize text properly. I would like to change the colours settings in all remote users profiles, but I don't know how. Could you please give me any advices?