For instructions on how to assign a lead to someone else click here

For an -in-depth understanding, please refer to the example below. 

Jane (merchant), decided that she wants to assign Charles' (staff member) Lead Brian to another staff member. From Core Setup, Jane clicked on the Lead module, which by default landed her on the Lead segment. 

She clicked on Brian's name which brought her to the Lead Detail segment.

Jane then clicked on the Activities segment and used the Assigned To drop-down menu on the right of her screen to change the staff member from Charles to Craig.

 Jane was then presented with a Lead Assigned Successfully message at the bottom of her screen.