How to change the title text on the sale email?

Question

How can I change the title text on the sale email?

I always get this in my email when I make an order,

Main Website Store: New Order # 100000016

I want to change it to,

[Name of my Store]: New Order # 100000016

Is it possible? where can I change it?

Also, in the sale email content,

Thank you for your order from Main Website Store. Once your package ships we will send an email with a link to track your order. If you have any questions about your order please contact us at support@example.com or call us at Monday - Friday, 8am - 5pm PST.

Your order confirmation is below. Thank you again for your business.

Where can I change all this? Especially Main Website Store?