Newspapers have several different departments- a news reporting department, which ostensibly attempts to be neutral and fair (but often isn't), and an editorial

Newspapers have several different departments- a news reporting department, which ostensibly attempts to be neutral and fair (but often isn't), and an editorial department, which is neither neutral, nor fair. The endorsement comes from the editorial side. I can't answer why we would want newspapers to endorse presidents- except that historically, newspapers played a big role in shaping public opinion (now mostly replaced by social media).