Go to settings/devices/storage.
Turn use YAMT off.
Turn off the Vita.
Insert sd2vita and card.
Turn on the Vita, ignore any format options.
HOW TO Format:
Go to settings/devices/storage.
Choose developer options.
Select TexFAT format GC-SD's storage (game card to SD adapter storage format DO NOT SELECT THIS IF YOUR SD IS ALREADY SET UP AS IT FORMATS YOUR CARD).
HOW TO Copy Memory card data over:
Go to VitaShell, press circle until you see all the mount points (ux0, ur0, etc.)
Press triangle and mount uma0 (it will mount your empty GC-SD).
Go to ux0, press down once to get off the ..., press triangle, select "Mark all".
Press triangle again and select copy.
Press circle to return to all the mount points uma0, ux0, ur0, etc).
Enter uma0, press triangle and paste.
HOW TO Set ux0 mount to game card sd adapter:
Go back to settings, devices, storage.
Make sure use YAMT is checked.
ux0 should be set to SD2Vita.
You can set uma0 to memory card or internal storage, but I don't recommend it (save, preserve the flash storage).
Restart.
If you don't have that option in yamt-
Download the new YAMT installer and uninstall, then reinstall YAMT version 4 lite or higher.
If you have a 3G OLED, install the full version so you can use the 3G-SD card adapter later.