Changing team site page layout and master page with powershell

I am very new to Powershell and Sharepoint 2013 and very sorry if I ask any silly question.

Can anyone help me with powershell script that can help us change the Masterpage and Pagelayouts of MySite's for all users. We are using Sharepoint 2013 on-premises version.

Any help will be greatly appreciated..

Thanks

Baskaran

BKPA