The setting is called: browser.cache.check_doc_frequency in Firefox
The default setting is 0, which corresponds to "Check for a new version of a page once per session (a session starts when the first application window opens and ends when the last application window closes)."
We recommend you change the setting to 1, which corresponds to "Check for a new version every time a page is loaded."
To change this:
- type about:config in the address line,
- agree that you'll be careful, then
- scroll down the list of variables to browser.cache.check_doc_frequency, and
- change it to 1.
Many thanks to Dan Semi at UW-River Falls and Brook Soltvedt at the Wisconsin Learn@UW utility for this question and solution!