Right now, each time you select a parameter, it removes the first graph and adds the new graph. But it doesn't line up to parameter1 and parameter2.

Example:

Parameter 1 – Parameter 2
Nitrogen – Chlorophyll

Graph 1 – Graph 2
Nitrogen – Chlorophyll

Now I change Parameter 2 to Silica:

Parameter 1 – Parameter 2
Nitrogen – Silica

Graph 1 – Graph 2
Silica – Nitrogen