Causes of yellowing leaves are hot, dry air (they don't like much above 60 deg C), sunlight and underwatering. It may be you're not watering enough - they do like plenty of water, but must not be left very wet or sitting in water in any outer tray or pot, otherwise the crown rots. The trick is to water when the surface of the compost feels just dry to the touch, water thoroughly, allowing the excess to drain away freely, then replace in its outer pot or tray.

Welcome to Grows on You Rosemary. I'm sure that you will love it on here. Take care, Richard :-)

A tip I've found works is to stand the pot on a dish of grit or small pebbles. Keep the pebbles damp and this keeps the air round the plant humid without soaking the compost. When you feel the pot does need watering you can just increase the amount of water in the dish until the compost gets damp, but dont leave the base of the pot in contact with actual water for longer than that. A north facing windowsill is much better than a very sunny one.

I think Bamboo means 60 deg F...!

lol

Erm... yes, I certainly do...thanks Rosie rose!