The FIMS window can be changed to one of three default sizes - small, medium and large.

To change your FIMS window size, select Tools > User preferences > All Other Preferences.  Choose Font_Size in the Option column and select the desired new size from the right Value column.

A Large window will fill a 600x800 size screen. Your monitor and display properties might not work with all the default sizes, so if you are having display issues, try a different size.

It will be necessary for you to close and re-open FIMS for the size to take affect.