After YEARS of waiting, Microsoft have finally figured out how to let us change our domain names! So for those of you who have CompanyName1.sharepoint.com, CompanyName4.sharepoint.com etc, or another creative name because you didn’t realise the impact at the time, you can now fix it; or if your company has changed names.
There are plenty of things to consider before doing this though and it requires running PowerShell scripts. Microsoft have written great instructions on the process, including a section on Low, Medium and High impact areas. Please make sure you read and understand everything before doing this change.