Some versions of the HRR216VXA have a single lever to adjust the rear height, while others use a separate lever for each rear wheel. Which type do you have?
I can post some exact diagrams for either. If you're not sure, on the back of the mower deck is a serial number sticker, look for the serial number in the form of MXXX-1234567 and share that with me so I can reference the correct materials/documents...