Hello Nitikorn,

Activate Developer Mode:

• Go to Settings > Activate Developer Mode.

Locate the Report:

• Go to Settings > Technical > Reports > Actions.
• Search for the report you want to rename (e.g., Purchase Order report). Find the report name.

Update the report name using below line.

(object.state in ('draft', 'sent') and 'Request for Quotation - %s' % (object.name) or                'Purchase Order - %s' % (object.name))

Thanks & Regards,

Name : Yahoo Baba

Email:  yahoobaba077@gmail.com

It just change name when click print.When I open document by link on browser tab title is PO id. I want to change that to PO name.

You can use the print_report_name property in your custom report declaration. 

<field name="print_report_name">(object.name)</field>

This will change the name of the pdf to the Purchase Orders name.

For Example: PO9283.pdf

Put this when you create your custom report in the ir_actions_report.xml file

Hope this helps.