HTML charset encoding in Notepad++ issue saving in Windows-1255

Question

I try to save an HTML page in Windows-1255, using Notaped++. I chose the relevant encoding (Encoding -> Character sets -> Hebrew -> Windows-1255) and defined the charset in the HTML header as:

<meta charset="windows-1255">.

but..it seems as if the page is still in UTF-8.

Checking code validation (in https://validator.w3.org) spotted errors:

• Error: Legacy encoding Windows-1255 used. Documents must use UTF-8.

• Error: The only allowed value for the charset attribute for the meta element is utf-8.

And the rendering suggest the same (symbols are displayed like in UTF-8).

Any suggestion?