Import items - Only available for sales - Not seen in purchases

Import items - Only available for sales - Not seen in purchases

Hello Community!

I'm just racking my brains trying to import items into Books and make them available for purchase.
It only makes them available for sales...but I can't find them when I want to make a purchase order or a vendor invoice.
I can only enable them for purchases, if I modify them manually and individually.
Does anyone know how to modify this in the import or, failing that, how to modify all items in mass?

I hope someone can help me...

Thanks