Global plugin that allows for relatively easy and efficient implementation of an in-game inventory system.
My inventory resets when I switch to another layout
It's becuase you most likely setup inventories on start of layout. As mentioned in the tutorial video, everytime you create inventory with the same name, the inventory is overwritten, so all data is lost. Please check on this article for some extra tips:
forconstruct.com/ultimate-inventory-system-basics
It's mostly the same as the video tutorial, but includes extra info.