Display should be First name + Last name

Hi Guys,

I have changed my last names to capitals and its not effecting in display name

I run the below script made the changes in AD lastnames

$targetUsers = Get-ADuser -SearchBase "OU=india,DC=study,DC=com" -Filter {Surname -Like "*"} | Select DistinguishedName, Surname
$targetUsers | foreach-object {

set-aduser $_ -Surname $_.surname.toupper()
}

now i want to change Display name as first + Last name.

So My Display name should be like = kiran MANNE

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Ram