Stock Price is controlled by Price indicator in Material Master. Moving average price and standard price. Stock debit and Credit amount varies if material is managed at moving price as each good receipt may increase or decrease the price of the material.
Whereas standard price, material is always valuated at fixed price. Any increase or decrease is posted to price difference account.
You can adopt following solution if there is need - Copy the movement type 262 and create a new movement type Z92 or 962. Then allow Ext. GA Amount in LC as Required or optional entry. You can find configuration path as follow Materials Management-->Inventory Management-->Goods issue/ Transfer posting-->Define screen selection.
Why I am recommending a another movement type, You can add reason to this movement type and in case different accounting behavior is required, it will be easy to achieve. You will separate authorization object so only selected users will be perform this action. Reporting will be easily available. When you are creating 962, make sure you considering reversal so you need to have 961 as copy of 261 as well. I hope this will help. But This is a workaround solution. Recommended to use standard behavior based on price control for movement type 261 and 262.
Ext