Why is heading format not applied

cf. the screenshot: I’ve copy/pasted some text from a pdf presentation
and inserted in in my document.
I want to use that text as a “Heading 3”.
But when I select the text and then go to the drop down menu “Apply Style” and select “Heading 3”, the text format and size is not applied.
Why? Thy


Try FormatClear Direct Formatting (Ctrl+M)


Select the text before you do that.