Editing in an external editor?

Version 1.2.4 Windows 10 64 bit
When I send text to external editor (Softmaker Office 2021 in my case) is it copy and paste to return it to Joplin or is there another way?

I edit using NotePad++. When I'm done, I close NotePad++ and "Save" the file upon exit. Then I'm returned to Joplin, where I click on the "Edit in external editor" icon (now a square, like a video player "stop" button), and all is done.

I would expect SO 2021 to behave accordingly.

Thanks. It didn't work like that, unfortunately, (no 'stop' button after saving) so I tried the same in Notepad++ but that didn't work either. Perhaps it's the beta editor - or me somehow...