Application Pool Name is IIS is in GUID format in IIS and *How to get name any powershell command ?*
Get-SPServiceApplicationPool | select name,id, ProcessAccountName Get-SPServiceApplicationPool | format-list
You might see some Aplication Pools listed in here, and showing up on SharePoint DropDowns, that have actually been deleted already. You can remove them with
Remove-SPServiceApplicationPool -Identity "My Application Pool To Remove"
If you want to change the service account, try
Set-SPServiceApplicationPool "My Application Pool To Change" -Account $account