How do I change the default setting for .eml files?

I started using a new mail client...Mailbird. I want to save certain emails in the external hard drive. Mailbird explained how to save them as *.eml files. However, when I try to open one, it defaulted to the built-in Windows 10 app called 'Mail'. So, I went to the default settings by file extension, and lo and behold it doesn't exist in the list.

Now what?

Any help would be appreciated. TIA.

No offense, I appreciate the help. I have already done all of those things. When I right click on an .eml file, and then click 'open with' and select Mailbird, nothing happens. I believe the reason is that there is no setting for .eml (see picture). I think I need to know the file extension for Mailbird, because .eml is an old MS file for Outlook, etc.

@therealsimpsons

Things are still a little messed up between the Classic and Universal Platforms so, you need to make the association in the classic control panel.
Only thing is, the classic control panel won't let you access classic 'File Associations' so, paste this in a Run box: explorer shell:::{17cd9488-1228-4b2f-88ce-4298e93e0966} -Microsoft.DefaultPrograms\pageFileAssoc and press Enter.

Create the association from there using the mailbird.exe in C:/ProgramFiles(86)/Mailbird



... then it'll show up in Settings!

I tried that, copied and pasted...whatever it is opened My Documents file..I still don't have a .eml file extension in the list after .emf Your post says, "and then create the file from there...what is "there" and what does it look like?

Edit: Also, there is no file in my Mailbird File in C: Drive Program Files (x86) named Mailbird.exe

I'm sorry it has taken me so long to respond. I have been busy with other things. Here are my questions about Dalchina's responses.

Perfect Dalchina! SOLVED Thank you, and the others who responded!!