I have had double airport manager tabs, missing GSX errors, sceneries installed but not activated errors, out of date installer errors, missing buildings on sceneries that are installed, active and updated. All because I made some stupid little mistake installing KIAH? I wish I had known.
No, your mistake was installing KIAH (or something else), using an OUTDATED installer. The tell tale, is your reference to the "double addon manager" tab, which can ONLY happen if you installed an OLD FSDT installer *after* you installed something using the new installer.
This has been explained many times on the forum: when we changed the installation method, from installing INTO the sim (with the old installers), to installing in a separate folder OUTSIDE the sim, the new installer would migrate all your existing installation from the old folder (into the sim), to the new one. This was made in order to save you from having to uninstall everything, re-download everything and reinstall everything, which would be absolutely silly, since the actual sceneries didn't really change, they only had to be moved in the new place, which is precisely what any new installer does. AND, it will also move the software modules (Addon Manager and Couatl) to the new shared folder outside the sim, and will update the DLL/EXE.XML in FSX, or stop using them altogether (in P3D 3.4 or 4.x) and use the new add-on.xml method instead.
So, if you do the normal thing, which is to install some of the new installer over an existing installation, everything will work, because the sceneries will be moved, and the Addon Manager/Couatl will be updated and read from the new single shared location.
But if you do the mistake of installing an OLDER installer (one that was released *before* June 2017, when we switched to the new system), it WILL create a big mess, with double Addon Manager entries, duplicated areas, and there's NOTHING we can do to prevent you from using an outdated installer, and this will happen, because the old installer doesn't know anything about the new locations, so it will go back to use the old DLL/EXE.XML files method, the old scenery.cfg method and location, and will create a separate copy of the scenery in each simulator you install into, opposed to the new single location shared folder.
So, that was your only mistake: installing something using the old installer AFTER you installed something using the newest one.
Of course, this can all be sorted out this way:
UNINSTALL- Uninstall everything, and reply YES to the question "Do you want to remove the Addon Manager ?"
- Don't forget to uninstall also a Stand-Alone Addon Manager, which is listed under "Virtuali Addon Manager X" in the Windows Control Panel, and reply YES to the question "Do you want to remove the Addon Manager ?" too
- If you installed the Qualitywings 757, uninstall that one too, and reply YES to the question "Do you want to remove the Addon Manager ?" too
- If you installed any Flightbeam scenery that use the Addon Manager, uninstall that one too, and reply YES to the question "Do you want to remove the Addon Manager ?" too
REINSTALL- If you have the Qualitywings 757, install this FIRST, because there's no newer installer for it.
- If you have some Flightbeam sceneries that use the Addon Manager and don't have a newer installer from Flightbeam (one that use the Flightbeam Manager) yet, install these FIRST
- Download all the updated FSDT installers and all the updated Flightbeam installers.
- Install both FSDT and Flightbeam sceneries using the latest installers.
- Don't forget to install GSX, because it's MANDATORY for all FSDT products that uses SODE jetways, which includes KIAH.
I have spent the last 3 days (probably 8 hours per day) trying to correct a problem with newly installed KIAH scenery and all I have to show for it is a headache
You should have asked support for this, instead. As you can see, my reply arrived just 5 hours your post, which was made at 3:02 AM, our time.