I am experiencing chronic cough with bright yellow phlegm or mucus. the mucus has changed from dark brown/black to yellow. i'm an ex smoker of 1 year?

Chronic bronchitis?: Congratulations on stopping smoking. But don't expect overnight recovery of your lungs and bronchial tree: it takes up to 5 years to recover from the effects of tobacco smoke. At only 1 year, you remain susceptible to bronchitis, pneumonia, etc. Less dark color of sputum usually is a good sign. But for sure check with your doctor and follow her advice. Good luck!