Unfortunately, our system does not permit the change of Usernames.
PIA account usernames are always a "p" followed by seven digits, and they remain the same for the duration of the account. For security reasons, PIA has purposely made it difficult for individuals to remember or guess your username information. Our service centers around the highest degree of security and privacy. This is just one of the various precautions we take to keep you, your information and connection safe.
You can change/create a custom password for your 'p' username via the Client Control Panel located on under our Accounts page on our website here.
For detailed instructions on how to do so please review the following article here.
Additionally, for more information on any restrictions of characters for your custom password please review this article here.