I work as a dietitian nurse in a kindergarten, taking samples and plan...

I work as a dietitian nurse in a kindergarten, taking samples and planning menus, but for some reason, the storekeeper decided that I should be the one to order the supplies. Previously, she was the one who ordered them and also planned the menu. I'm new here. Planning the menu is fine, as it's part of my duties, but I'm unsure about ordering the supplies. I approached the head about this, and she agreed with the storekeeper, saying that I should order the supplies. For those who have worked as a dietitian nurse in a kindergarten, I would like to know if this is really the case? Perhaps the storekeeper decided to shift the responsibility of ordering supplies onto me.