How do I adjust the inventory quantity to avoid getting a low inventory warning?
You may adjust inventory in two places. First, you may set up default inventory rules at Settings / Edit Site Options / Inventory Control. That would set up global rules for all products. Additionally, in the create / edit product screen, you override these default settings to set inventory levels at the individual product level. This can be found midway down the first page of the edit / new product screen on the right-hand side.