The below will show you how to use your sales history to reassess your stock items' safe levels. This will help you determine which stock items need to be reordered as the safe level will be based on past sales, rather than an estimated safe level.
Usage
Review Safe Level Reassess settings in System Values | Purchasing.
In Stock Tools open the Reorder Report.
Green-select the stock items whose safe levels are to be reassessed.
Use the Actions menu to select Reassess Safe Levels.