This is an easy script to change the people picker if your organisation has multiple domains.
For example, if you have one forest (sprocks.io) and a domain (sprocks.us) in your organisation, the script would look like this:
Add-PSSnapin Microsoft.SharePoint.Powershell -EA 0
stsadm -o setapppassword -password FARMACCOUNTPW
stsadm -o setproperty -url http://centraladminurl -pn "peoplepicker-searchadforests" -pv "forest:sprocks.io;domain:sprocks.us,USERNAME,PASSWORD"
It is important to note that USERNAME and PASSWORD belong to a user that has access to both domains and is allowed to search them.
Also you will have to run "Add-PSSnapin Microsoft.SharePoint.Powershell -EA 0" to use stsadm commands in PowerShell.