Change language totally, not just "display language"

I want to change my Windows 10 language completely.

I started in the "Regions", added a few languages useful to me like Swedish, English and a few more.

I removed the original Norwegian there, and set "Display Language" to US English.

In most places this works fine. US English displays. This is necessary since all help on the internet is always in US English.

But in a lot of places, this does not work.

A few examples:

1 When I start the computer, the welcome screen first shows the time and date in Norwegian, as in "23. Mai". A second later it changes to the US equivalent "23 May".

2 When I want to "reset" the computer, the control panel is ok, but a few clicks ahead, when Windows may no longer be active, it reverts to a series of Norwegian textst, starting with "vent litt" (meaning wait a bit) and then proceeds to guiding me in Norwegian how to reset the computer.

How do I change these texts to English?