If you want to set a password to never expire for a single user, you have to do it via PowerShell. There is no way from admin center.
Download and install the following modules.
- Microsoft Online Service Sign-in Assistant for IT Professionals RTW
- Windows Azure Active Directory Module for Windows PowerShell (64-bit version)
-Open PowerShell with elevated privileges.
-Execute the following command. When you are prompted, enter your O365 global admin account or an account having required privileges.
$credential = Get-Credential
-Execute the following command to connect to O365.
Connect-MsolService -Credential $credential
-Execute the following command to set an individual user to never to expire.
Set-MsolUser -UserPrincipalName <name of the account> -PasswordNeverExpires $true
For example, to set the password to never expire for a user 'John Powell', Issue the following command.
Set-MsolUser -UserPrincipalName firstname.lastname@example.org -PasswordNeverExpires $true