Bold Setting on Coffee Maker
All other things being equal (water, bean, grind, filter...) the "mechanical" effect of a bold setting is to constrict the flow rate so that the water is perculating with the coffee for a longer period, thus rendering a 'stronger' (or more bold) flavor. (see https://cooking.stackexchange.com/a/20202/6279) 

If you feel like your coffee maker is 'stuck on bold' I would give the machine a thorough cleaning as the flow control is probably 'stuck'. I don't know that I would say clean after every use (if you use it daily...) but you are probably long overdue for a deep cleaning .