You must be using an X11 server set to PseudoColor (indexed color) mode, rather than TrueColor. You have the following options:

a) have your sysadmin setup your computer to run in TrueColor mode; how this is done depends on the system you are using (Linux, Solaris, ...). If practicable, I recommend this approach. However, there are some older X11 programs out there that don't work with TrueColor, and if you are dependent on one of them, then TrueColor won't work for you.

b) you can use the "New" button (lower left of AFNI controller window) to open a new controller, which can then be used to view a separate dataset. If you do this, you can also use the "Define Datamode->Lock" menu to lock the two viewers together so that the crosshair locations are synced (i.e., click in brain #1 and the crosshairs also change for brain #2). This lock feature is only useful if the (x,y,z) coordinates of the two datasets you are viewing are matched anatomically, of course.

c) you could try to run each copy of AFNI with fewer than 80 colors; for example, "afni -ncol 40". However, this may not work any better than the current situation.

bob cox