From the ‘Share & Assign’, you can Assign Owner for the selected record.
You can assign any record to specific user or team by clicking on “Assign Owner” option from specific user’s details. 
Selecting Assign Owner option, it opens a dialog box where dropdown list of all the CRM users is provided to select user or team as required. After selecting the appropriate User/Team, click on Assign button. 
Note: When assigning record to a user or team, that specific user or team should have role assigned to it or else record won’t be assigned.