Purpose of "Load" in Scopy signal generator configuration GUI

What does the "Load(Ohms)" input box in the configuration GUI for the signal generator in Scopy (version 1.4.1) do?  When should it be set to something other than "Inf"?  I measure that the analog outputs have an output impedance of about 50 Ohms.  Does this setting change something?  Here is a picture of the input box.

By the way, despite occasional Scopy crashes, I like it and the ADALM2000 very much.  Most Scopy settings are self-evident.  It is a sign of good interface design.

Thanks.