Hi World_Extreme,
You mentioned after changing the name servers, the website is viewable, but cannot be edited. Would you please tell me the detailed steps you have performed?
For Office 365 P plan, you can move your emails to Office 365, and keep your current website. Before you change the name server (NS) records to point to Office 365 name servers, you need to create a DNS A record in DNS manager that points to the IP address for your website. For detailed information, take a look at this article:
Move your email to Office 365 and keep your current public-facing website
After this, emails will be delivered to Office 365, but traffic to your website will go to your current hosting provider.
Thanks,
Young Yang