How to set Calibre directory?

[joe at actionline.com]

When I tried to install Calibre, the installation created a long directory
name with Capital letters and a space in the file/directory name in my top
user directory, and I have not been able to figure out how to stipulate a
short, all lower-case directory name with no spaces in it for my
installation.

Surely there must be a way to avoid that long/awkward directory name, but
how?