Originally Posted by Blossom
No there is no option in ES File Explorer for this. I wish there was.
I'm glad you got it to work. However, you misunderstand the purpose for my post. ES File Explorer should never have a Launch By Default when managing it under Applications.
The reason I bring this up is because other Apps will. For example, say you have two PDF Readers, Mantano and the Kindle Reader. The Kindle Stock PDF Reader (Quick Office) is probably the Launch by Default App because it was installed first. If you were to touch a PDF in ES File Explorer the Kindle App would display it be default. If you want Mantano to display it, you have to Clear Defaults under Launch by default for Quick Office in the Applications Manager. The next time you touch a PDF in ES File Explorer the Fire will prompt you and ask you what App you want to use to open the PDF. You can check Use as Default and then Mantano and every time you launch any PDF Mantano will open. This is a very common problem people have when trying to change default web browsers in Android. They want to use Opera by default, but every time they try to surf with Opera the Stock Browser pops up by default. If you want to use Opera by default you have to Clear the Defaults in the Launch by Default section of the Application Manager for the Stock Browser. The next time you surf with Opera you will be prompted as to which browser you want to use at which point you can check Use as default and then select Opera.
It shouldn't matter what File Explorer you use, once you touch the file and it has an App associated by default, the default App will open it.
Which brings me full circle. If you download a book or any other file and the Fire asks you do you want to "Open As..." with "Music", "Video", "Text", "Choose Applications" as the choices, be careful which one you select because you could inadvertently assign a File to an App that really won't open it, and the next time you download a similar file Android will try to open it again with the same App if it is instructed to do so by default.
I hope this isn't too confusing. It's pretty important to know especially when you decide you prefer and want to use one App over another and the other App keeps forcing itself open by default.
Anyway, I'm very happy to see you got the problem solved.