If you wish to set the timer in a 24-hour or 12-hour format, you can select either option in your phone's settings (Settings - System Management - Date & Time - 24-hour format). Then, the timer in the app will also display in the chosen format.
If changing the device's time format doesn't affect the timer display, you can try clicking on the device page and check if there is a time setting option available to modify. If such an option doesn't exist, it is possible that the device itself does not support adjustment of the time format.
Note: If it is a 12-hour system, there will be AM and PM options next to the time for selection. After the mobile phone time format is changed, the time format of the history records (message push, device usage record, and video recording, etc.) in the App will not be changed. Only records after the time format changed will use the new time format.