Why does this language switcher partial not appear?

I am new to Hugo and know only the basics about .html etc.

I try to set up a website using the techdoc theme because I want it to show documentation. This documentation is in 2 languages (possibly, but unlikely, more in the future).

I use the “same directory with language ending” option, which seems to work.

Aside Question: I can only see one language, and switch it using the weight in the config. But that is global, meaning the second will never be shown? Can I set it to “browser language” or “system language”? Changing those did not change the sown language.
/Aside

To switch the language I found a thread here in the forum and decided that this version is the most fitting for my purpose:

It uses a partial “langswitcher.html”.
I tried to put it into the single.html and the individual pages, but it does not seem to alter the site and display the language dropdown.

  1. Where would be the correct place to put the langswitcher? In the single like here?
{{- define "main" -}}
<h1>{{ .Title }}</h1>
{{- partial "langswitcher.html" . -}}
{{- partial "table-of-contents.html" . -}}
{{- .Content -}}
{{- partial "edit-meta.html" . -}}
{{- partial "pagination.html" . -}}
{{- end -}}

I would prefer to have global switch in e.g. the header, but that might not work with the code?

  1. If that is correct, why isn’t it showing up anywhere, do I need to add it somewhere else?

I found that I had to put it into baseof.html instead of single.

Though it’s not a dropdown but a list?? But at least it works, which is a good start.