Dragon Tree (from B&Q) starting to turn light green/yellow. Any advice for a first timer?

Hi All,

I’m new to the community so firstly, hello!

I bought a dragon tree from B&Q a few weeks ago for my office/study. When bought, it was dark green and now the central leaves are starting to turn light yellow/light green. One leaf has fallen off today. I’ve shared some photos for reference.

Can somebody please advise on what to do next and how to ensure this plant remains in good health?

(PS: instructions say you shouldn’t over water so I’ve only watered it once since I bought it a few weeks ago).

Thank you!