Background images on client and host systems change

I only use this software to assist parents from time to time.  When I accessed their desktop the first time from laptop, MY background image became theirs.  When I changed theirs back to what it was prior to connecting, physically at their system, the background image on my laptop then changed to match theirs.  I have only connected twice to their system.  But every time I change the background image on one system, the other system automatically changes to match!  Neither system as the other’s image on their system.  The only connection is teamviewer.  Please help!