You can do this through Power Shell. The following link has a video that makes this task easy.

https://support.office.com/en-us/article/Set-an-individual-user-s-password-to-never-expire-f493e3af-e1d8-4668-9211-230c245a0466?ui=en-US&rs=en-US&ad=US

Downloads:

Download and install the Microsoft Online Services Sign-In Assistant for IT Professionals RTW from the Microsoft Download Center.

https://www.microsoft.com/en-us/download/confirmation.aspx?id=28177

Download and install the Azure Active Directory Module for Windows PowerShell (64-bit version).  The file you are looking for is named “WindowsAzurePowershellGet.3f.3f.3fnew.exe”

I found it on the following page, at the bottom under the heading “PowerShell” and “Windows install”.

https://azure.microsoft.com/en-us/downloads/

Once you install the Active Directory Module you will need to restart your machine. Open the Powershell as an Administrator.

Once you type in the cmdlet: Connect-MsolService    , and hit enter you will be prompted for login credentials.

Use the Office 365 admin credentials.

The next line to type in is:    Set-MsolUser -UserPrincipalName theemailaccount@thedomain.com -PasswordNeverExpires $true         , hit enter.

You are done.

I hope this helps someone else out there……