why cannot I set assignee from component lead as project manager role?

[Arnold Chang]

why cannot I set assignee from component lead as project manager role?

[Jamil Rahimov]

@Arnold Chang 
You can set user or group to project role with following steps:
Projects -> "Project_Name"->User and Roles -> then Add users to a role:

[Jamil Rahimov]

@Arnold Chang 
And what is component lead? can you give brief information?

[John M Funk]

Hi Arnold - Welcome to the Atlassian Community!

Unfortunately, you can only choose the Project Default or Project Lead role for the default assignee to a Component. You cannot use other Project Roles.