Where is this template stored? There is a save-to-disk template for the filename, and Metadata Plugboards which control the title fields. Furthermore, the save-to-disk template can get overridden by the per-device setting in the device driver (if it was ever edited, it will save the configuration even for fields not explicitly set) -- this sometimes confuses the apprentices
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With a tablet, I believe you need to set the filename in the device driver, as it requires configuring anyway. So -- select "Configure this device" from the dropdown by Device in the toolbar. And change the save template there.
MiniMouse's advice for the actual formatting is solid, I cannot add on it.
But keep in mind, if it is a filename, you can use "/" in the save path to delineate folders.