The ‘use legacy console’ option has nothing to do with the ability to run 16-bit applications, it only controls the new terminal. In particular, it will not make EDIT work on 64-bit Windows. Roger Bassaber is either running 32-bit Windows 10 (possibly on 64-bit hardware), or using a different 32-bit or 64-bit editor that also happens to be called EDIT, or lying.
To get EDIT to work on 64-bit Windows, the easiest way is this:
First, download EDIT.COM, it's very easy to find and get online.
Second, download DOSBox.
Third, place a batch file next to the DOSBox executable with the following contents:
%0\..\dosbox -noconsole -forcescaler hq2x -c "mount a \"%~dp1\"" -c "mount c \"C:\Program Files (x86)\DOS\"" -c "c:edit /64 a:%~nxs1" -c exit
This assumes that you placed EDIT.COM in the folder C:\Program Files (x86)\DOS
. You can change the settings as you like. The settings shown here will hide the annoying DOSBox console, enlarge the text to avoid eye-strain when using modern displays, load the file as a binary file with 64 characters per line, and quit DOSBox when EDIT is closed. You could for example remove the /64 to load the file as a text file or add /H to get more rows of text on screen.
You can now drop a file on this batch file to open it in EDIT or invoke the batch file from the command line with the file to edit as the argument.
notepad.exe %1
. Another alternative is to use echo to create small text files as suggested in answer to a similar question posted here at Microsoft.com.