Hi גדיאלוני, there is a known bug in the 1803 version of Windows 10. Microsoft are aware of this issue and hopefully are working on a patch . . .
For the moment, please try this workaround to set your preferred input language:
Right click your Start Button, choose Powershell (admin)
Run this command to get a list of installed languages on your PC
Get-WinUserLanguageList
Note down the LanguageTag of your preferred language
If say, your preferred language is US English, run this command and hit Enter:
$1 = New-WinUserLanguageList en-US
Then run this command to set the order of installed input languages
Set-WinUserLanguageList $1
Close Powershell and restart your PC