Ok I haven't watched after BFG either so I can only lay out what happened before then.
Cornette was the original GM and Jarrett had no power other then being the founder. Foley came in and as an investor and was made the executive shareholder by Dixie and Cornette was gone. Suddenly as founder Jarrett had some power but Foley was the "real" general manager as executive shareholder.
Then when Hogan and Bisch came in Hogan was Dixie's business partner and in charge of the wrestling and Dixie revoked all the powers that Jarrett as founder and Foley as shareholder had. So now they where just minority shareholders/ founder.
This means that from that point on Hogan was in charge of the wrestling aspect and Bisch was his appointed GM for a comparison think Dixie as pre campaign CEO and majority owner for real Linda and Hogan as on screen minority owner Vince, with Bisch as Theodore Long.
Now the whole goal of Immortal was/is to take over full control of TNA as they feel Dixie is/was meddling too much in the wrestling aspect and/or Immortal was just greedy and wants everything. Now Dixie signed over full control of TNA on before the glory but as long as the legality of that is still in dispute neither side can exercise any of the "extra" power that comes with it. So Immortal have robbed Dixie of some power but have not gained that same power as of yet.
I know this is in very brief and I haven't followed the latest episodes but this is as far as I can surmise it. Picking apart Russo's brain it's an experience you want to forget lolz. (although he does get some unfair flack as BFG, Turning Point, Final Res 2009 was him on his own booking for the first time and was good.)