hue saturation adjustment effects all layers

If you told us what instructions you have followed and give us a screenshot of your screen with the layers panel visible, perhaps we might be able to figure out where you are going wrong.

Are you able to create the Clipping Mask?

If you want any adjustment layer to affect only the layer directly below you can make a Clipping Mask by having the Adjustment Layer active and going to Layer>Create Clipping Mask or click the Create Clipping Mask button at the bottom left of the Adjustment Layers panel.

Are you using an Hue/Saturation Adjustment Layer or Enhance>Adjust Color>Adjust Hue/Saturation?

Can you post a screenshot?

You need to make a selection of the area you want to change and then create the adjustment layer.  In the following screenshots, I have created two new layers from a selection on the original layer (the flower and the green leaves on the left).  I then applied a hue adjustment layer to each.  Let us know if you still have questions.  If you do, please give us a screenshot of the image and your layers panel.