Password expiration in CRM Online is indeed a nuisance and can be changed but the maximum password expiration period configurable using Office 365 administration portal is 2 years. If you intend to use O365/CRM Online for longer than 2 years, you may want to consider using Powershell tools to do it like a boss.
The following instructions are applicable to Windows 8 x64 machine and are abridged version of managing Azure AD using Windows PowerShell:
- Install Microsoft Online Services Sign-In Assistant
- Install Azure Active Directory Module for Windows PowerShell (64-bit version)
- Start Windows Powershell and run the following script:
Connect-MsolService Set-MsolUser -UserPrincipalName <user ID> ` -PasswordNeverExpires $true # The following line will do it for all users. Get-MSOLUser | Set-MsolUser ` -PasswordNeverExpires $true