There’s a firmware update available for the Canon EOS 6D. It can be downloaded from the Canon website via the link below. This new firmware is v1.1.3 and according to Canon it “fixes a phenomenon in which the Date/Time/Zone settings screen appears on the LCD display, after the user has already configured these settings. The values for the Date/Time settings may reset if the backup functions which retain those values do not perform properly. Even if the camera does not exhibit this phenomenon currently, it may in the future. Accordingly, we recommend that you update the Firmware in the camera to version 1.1.3 as soon as possible”