Make sure that whenever you change any settings using the injector, that you press the create config file button. It will put a file on the sd card with the checked settings enabled.
View attachment 213175
You should also be able to change the settings before starting the game.
View attachment 213176
Enable Memcard emulation to enable the memory card. Set the block size to your desired capacity. Higher numbers create memcards with more storage that can hold more game saves, but considered unsafe because some games may not be able to save properly. Turn Memcard Multi on makes it so that a memory card is created for each game instead of only one memory card for all games.