Why cannot change owner name in sales invoice and delivery order ?

Because you have linked the Sales invoice to DO. When you want to change the owner name in sales invoice or DO , will not be changed.

1. please go to my biztory >delivery order > auto generate change to (with selected items when delivered)  > untick the update DO when sale invoice is Updated > saved the changes.

2. "When creating a sales invoice, the associated delivery order will not be automatically saved/generated.

3.  Manually create the  Delivery order and input the owner's name > saved.