As a general rule people accept written text over oral communication.
To some degree this can be explained by the apparent permanence of written text. The obvious vicissitudes to which the spoken word is subject - the misheard word, the exaggeration of stories, the fabrication of a new version of events - appear to be inapplicable to written text.
The veneration of written words is most clearly seen in the concept of a Holy Book. Something written is seen as unchanging and a reflection of the eternal. Put in a more mundane way, until recently at least, people believed in newspapers in part because something that was written was seen as carrying a high inherent truth value.
And historically, at least for newspapers, there was reason to believe what was written. The investment required to print a newspaper or book or magazine was so high that publishers were careful to ensure their materials reflected, if not truth, then at least accepted opinion.
Now this belief in the written word may be changing. The printed text is rapidly being replaced by the electronic screen. And most consumers of electronic media are well aware that nonsense is common online. Showing that something is available online is not the same as showing it is true. Anyone can have a blog - and that suggests truth may not necessarily be a part of all online media