The way the OS works is that - for most apps - all references in the file system to the SD card use the volume label e.g. 334D-55FC. If you change the SD card (e.g. I went from 64GB to 200GB) the volume label changes, and anything installed on the card, plus anything installed in main memory which references the SD card, stops working. For example Tomtom won't start (and I am not talking about the TT startup bug - that is related to the All-Europe database file, mainly). You have to uninstall it and reinstall it with the new card in place. The Quickpic image viewer does the same thing. I have tried to rename the volume label of the new card to be the same as the old one but that doesn't do it. The OS seems to use a volume serial number. A strange system!