Manual availability changes are not permitted since they do not update product costs and revenues. All item movements have to be done through the issue of Goods Inbound, Goods Transfer and Goods Outbound documents. If you want to perform batch operations, you should update the availability by creating Inventory Transaction Documents using the Data Import tool.
In case you want to do a Physical Inventory and adjust the Megaventory stock quantity levels according to a physical count, you should go to the Inventory Taking page, download the excel template and upload it to Megaventory.
Or login to your account.