faeran

In LaunchBox, open up Tools > Options, and find your Screenshot Priorities. Move up the gameplay image types to the top of the list.

If I had to guess, you probably set up RetroArch a long time ago and your associated platforms section doesn't quite match with our current server defaults, as in it's missing the default Atari 2600 associated platform configuration.
In your instance, you'd want to simply choose to Manually Configure Emulator and choose your RetroArch emulator. Like you noticed, choosing the Install RetroArch option would install another instance of RetroArch, similar to going into the Manage Emulator window, Adding a new emulator, choosing RetroArch and hitting the download button.
You could also go into your RetroArch emulator window, add a line for Atari 2600, then run the ROM Import Wizard, and you wouldn't see that page.
Basically, you are only seeing this due to a mis-match between your old emulator config and the one we use on our server. Luckily we can update the RetroArch integration plugin to make this less confusing for users in the future.
 
 
 

This will only work if you use a Non-merged set.
But, you could go to your Arcade platform, select all the games, and run the Tools > File Management > Export/Copy ROM files from Selected Games to New Folder...
It will make a copy of all your imported games into a new folder, which should work out to about 20GB.
This won't bring over your CHD files, but if you have the CHD Requred playlist you could identify which CHD games you have, and manually move over the ones you have ROMs for.
This part of the MAME video shows it in action:
Again, this will only work if you use a non-merged set.
 

With Android, if you added games to a game directory, you would need to run the import game tool again.
For example, let's say you import 50 master system games into LaunchBox for Android, then you now add 5 extra master system games into the same folder on your Android device. If you run the import tool again, it will tell you that it found the extra 5 games and allow you to bring them in.
In the future, we may make this more clear in the app and provide some kind of scan tools, which would save a few clicks.

The answer to this is always send an email to support@unbrokensoftware.com

Sounds like you accidentally cancelled the install while it was messing with app files.
Go into your LaunchBox\Updates folder and run the 13.17 setup file. When you get to the part where it asks where you want to install it to, choose your current LaunchBox folder. Double check the path before hitting next and make sure it's correct, as the setup likes to add an extra "LaunchBox" folder into it.
Once you finish the install, LaunchBox will open and you'll see your library.

What does your 3D Cart Priorities look like under Tools > Options?
 

I could be forgetting something, but I'm fairly sure LaunchBox doesn't track achievements from the Epic Games Store.

This issue has been resolved internally and will be out when beta 2 drops.
If you would like to help test the beta, here's the link:
 

The issue you are having is that you are trying to use the clear logo image type for an image that's not a clear logo, which is why you are seeing it show up in the spot that you are.
To use your example, this is a clear logo.

This is a fanart background:

Here's what those 2 look like in the playlist details:

Unfortunately, things are more isolated on Android. If the Android app has an exit button, that would be the easiest way to get back to LaunchBox. Most emulators have something like this built in, but each app would need to individually support some kind of exit button.

The only reason I've ever seen for the play button to not exist is if the ROM file the game is pointing to is inaccessible. If this is the case though, the button gets replaced with text that should read something like "unavailable".
 

Go into Tools > Manage > Emulators
Find your RetroArch emulator and edit it. Click the Update button.

After setting the button, restart LaunchBox, and see if that makes it work.

Device images have always been something you had to manually add into LaunchBox, so it sounds like sometime in the past you must have gone through that ritual
 

You can switch them, but only one at a time. Holding down on one of the platforms to open its menu and choose Edit Media and replace the Banner Image. Make sure the banner is the same size, I think they are 384x1080 if I remember correctly.