How does one configure Notepad++ to use spaces instead of tabs? – Stack Overflow
Posted by jpluimers on 2017/09/27
The StackOverflow screenshot it out-dated so a new one is below.
- In the
Settingsmenu, choosePreferences... - In the
Preferencesdialog, chooseLanguage - Ensure the (default empty)
Replace by spacecheckbox is checked - Optionally change the
Tab sizefrom 4 to another suitable value
I prefer these settings: 
via: How does one configure Notepad++ to use spaces instead of tabs? – Stack Overflow [WayBack]
–jeroen
`Replace by space` and `Tab size` settings are under `Language`
The Wiert Corner - irregular stream of stuff 
joho68 said
Spaces should be the default, in all applications, at any given time. As should Emacs keyboard emulation :) Notepad++ is one nice and versatile piece of software though!