214-226-9138

criminal call forwarding showed up on my phone bill
i never use call forwarding, intercepted call

Apparently some of my calls are forwarded to this number 214-226-9138. This is fraud!

I'm pretty sure it's just your voicemail

214-226-9138 is a number for AT&T voicemail.  Your phone forwards to voicemail if it is not answered or if it is turned off.   I was concerned about this, too.  I thought someone had turned off the ringer and had directed all incoming calls to their  number to defeat two-factor authentication.  The guy at AT&T customer service explained to me that I had probably set the volume to zero via the switch on the side of the phone.

Why am I not able to change the forward phone number

Why wouldn't you ask that to your service provider instead of a number look up site?

(214) 226-9138 my fone said call fwding was Active to this number as well . Wth?

This is likely the number your carrier uses to forward your calls to voicemail.  Check with your carrier.