The "Mark all as read" button is disabled on the all stories view on iOS.
I'd love to have this enabled too. Have it mark all stories that have been loaded as read. I like to browse the headlines and read what interests me. I don't always read every single story. It is time consuming when using the ipad/iphone app to have to go into each folder to mark them as read. I have yet to find a way to do so if there is. Keep up the great work! You converted me into a paying customer after 2days of usage.
Yup, if you want to get it, I have an experimental beta out. Visit this link on your iOS device: http://www.newsblur.com/ios/download. You'll get an enabled mark as read button in All Stories, as well as side-swiping stories, and intelligence training on authors and tags. I'm planning to submit it later this week, but the beta should work well.