If I bought the Windows 10 edition of Minecraft in the microsoft store, can I change it and play the Java edition?
No, unfortunately that will not work.
Yes you can give the game back normally it doesn't work but at that time I called Microsoft then it worked, I had my money again and bought the Java Edition.
Do you know how it is with a prepaid card whether I still get money back?
This will not work with a code
No, the Java edition also costs a lot more as far as I know
So I bought it through Paypal, you have to call Microsoft support
You may get the code back but maybe you can sell on eBay
No the Java edition costs less
This Minecraft, which is in the Windows Store, is "Minecraft Bedrock", a version of Minecraft that is cross-platform for servers. If you're lucky, Microsoft will give you the money back because you made a mistake. This is a completely different Minecraft and has nothing to do with the actual Java edition.