Assign a new owner to multiple records at one time
With the winter’19 Salesforce release, we can assign a new owner up to two-hundred selected records by using Change Owner button in the page level action menu in a list view or related list in standard table mode or related list quick links.
This feature is available for lead, case, or custom objects in lightning version.
On case list view:
On the case related list on the account record
Make sure that you have edit permission to the selected record to update the owner.
To know more about this refer this URL: https://releasenotes.docs.salesforce.com/en-us/winter19/release-notes/rn_lex_change_owner.htm