I assume that you are talking about Project-GC statistics as displayed on your profile on geocaching.com. If so, you can change the units shown there with the "export language" setting on Statistics -> Profile Statistics -> Settings.
The units setting in your personal settings affect what units you see when browsing the site. The type of units other people see when looking on your personal statistics is controlled by the setting described above, and when you yourself are looking at your statistics via your profile on geocaching.com, you are considered "other people" since the same image is shown to everyone in that scenario.