Thank you for your prompt reply. What I am trying to do is as below.
1. More 1 SKU from 4 different bins to 1 bin. and then make the new bin as fixed and default. Inventory in the other 3 bins has already been moved to 1 bin and the other bins are all empty.
As a result, 1 SKU , 4 bins have been moved to 1 SKU 1 bin and now I want to make the new bin as default and fixed bin.
System is not letting me do it.
Not sure how to solve this.