I have the problem, that no pushback is available. Looked in forum, found out that i can manual set the setting for each airport and parking position.
You are not required to do that. The pushback parking position is taken from the scenery AFCAD so, I hope was clear to you that this wasn't you "had" to do just to have the Pushback working on any airport. It was ONLY needed at those specific 3rd party airports the developers FORGOT to set a pushback direction, so it was set to "None"
Every default scenery and every FSDT and other developers sceneries made with enough care, DO correctly set the pushback direction, so there's no intervention needed.
I can not say what i have changed, but now in every airport (except the fsdreamteam KLAX and KLAS) is the pushback set to "none" and i have to chance every parking spot to "both". - Thats a lot of work -
Each customization file you create, will act on just ONE airport, the one it was created for. It's not possible that would all change to "None" automatically, nothing in the whole GSX program has a way to set some kind of "global" override of the pushback direction.
That's not normal, and it cannot happen, unless you did it explicitly: manually selected each airport, selected the "root" node of the list, which will select all parkings ( I hope you knew you could do that ) at once, and select "None" then Apply the changes. Repeat this for each airport.
As you say, it is a lot of work, so it's not possible you might have done it by mistake.
Unless, you are not really referring to "every" airport, but just to those 3rd party airports that originally had the pushback preference to "None" so, you simply LOST your customization files, so they all reverted to the initial situation, which means you should go it again.
I can only confirm this cannot happen normally, unless you did something to reset your GSX preferences, like trashing the whole %APPDATA%\Virtuali folder, which will remove every customization you made to plane and airports.
