If you want to sell a specific item regardless of the available quantity, mark it as Replenishable. There is a replenishable checkbox on the Product General page. When updating various channels, SellerCloud sends a fixed quantity for replenishable products, so it consistently shows a specific available quantity.
For eBay, it will look at the value in the Fixed Price Quantity field.
For Amazon, use the Fixed Quantity setting on the Amazon Properties page.
On most channel properties pages, you may need to check a box to reveal the Default qty field.
When set to Replenishable, the Safety Quantity is ignored.
To update the Replenishable field in bulk, use the Custom Export feature from the Action Menu on the Inventory Management Page. The related field is Replenishable and accepts values of True or False.