First you need to make sure you have the Azure AD Module installed on the computer.
If you do not have the the Azure AD Module installed you need to:
Open PowerShell as administrator
Run the command
(get-item C:\Windows\System32\WindowsPowerShell\v1.0\Modules\MSOnline\Microsoft.Online.Administration.Automation.PSModule.dll).VersionInfo.FileVersion

Then you need to run the following commands in powershell:
$msolcred = get-credential
connect-msolservice -credential $msolcred
Get-MSOLUser | Set-MsolUser -PasswordNeverExpires $true
You can check if this has worked by running the following command in powershell
Get-MSOLUser | Select UserPrincipalName, PasswordNeverExpires