The FrameMaker installation was subtle. I didn't notice it until we got to our spell-check exercise and we watched as FrameMaker flagged "color" and wanted to replace it with "colour." InDesign was more obvious, starting with new documents defaulting to metric measurements and an A4 paper size.
Both students live and work in the U.S., and both wanted to convert their installation back to English US. Unfortunately, the language option for both programs is selected during the installation of the software, and by the time we caught on, the decision was well in the past. So what can be done?
The simplest answer is to deactivate the program (leave the serial number on the system), uninstall it and then reinstall it. This time, slow down and read the prompts. Choose English US when asked, and then complete the installation.
One could also tweek the International English version to work with US English. Both programs allow you to change defaults: you'll want to change the dictionary language default, measurement defaults, etc. Be aware, however, that unless you uninstall/reinstall, the menus and dialog boxes will still show the International English spelling.