Do you have any sample text of where this happens?
I was not able to replicate this issue, but I do know that after changing the option, the changes may not appear immediately since the unit conversion only happens as the text is outputted. So if there is text already output, it will need to be output again in order to display the chosen units. Also note that written passages do not always reflect the units since that is the decision of the author. The unit setting is mainly for the codex stat displays.