Aura HD Mark as read prompt

If I leave a book at 98% or 99% and the last read date is long enough ago, Kobo prompts me to mark it as read. Recently I hit the wrong button and end up marking a bunch of recently-updated fanfics (with the percent read manually set to 98%) as read. Is there any way to disable this?

Alternately: What's the lowest percentage that can trigger the prompt? I can just set it to one below that.

:thanks: