WordPress App publishes wrong byline

Every time I use an ios or desktop WP app to post to my site, the post invariably appears under a colleague’s name. The only way to fix it is to open the full version in any browser then I can change the byline manually.

The problem does not occur when I use a browser either via WP.com or directly via my self hosted site. I’ve looked for a setting to correct the error in both desktop and iOS apps and can’t find one. Anyone got any ideas?