Step 1 - From Listing Screen, select Sales.

Step 2 - Scroll down and go to current listing tab. Filter and select all the published listings. Click Bulk Update. Check if the selected records are correct. Choose assigned user from the field.

Step 3 - Select the desired user on the set value. Tick the box if you like to assign the Listing Owner to this User. Then click update fields. Click confirm. You will know that the update is complete if the pop up window shows updated successfully. The update will show on all the selected records.