You could do something like this
$vmName = 'MYVM'Get-VM -Name $vmName | ForEach-Object -Process {
Set-VM -VM $_ -Notes $_.Notes.Replace('development','infratema') -Confirm:$false
}
If you want to do this for all VMs, you could do
Get-VM -Name
$vmName |Where{$_.Notes -match 'development'} |
ForEach-Object -Process {
Set-VM -VM $_ -Notes $_.Notes.Replace('development','infratema') -Confirm:$false
}