On my curves I normally plot them together, generate their fit plots and after, overlay the fit curves in the original plot.
For doing that, I add each fit curve one by one using the "figure properties" window. Now, the problem is the following:
Depending on where you click, the fit curve won't be added correctly.
Here I attach an image in which I've drawn red and blue circles over the figure properties window. If you click on the red circle in the list, the curve added won't be the selected one, just the previous one. If you click on the blue circle the curve added will be the correct one.
Example: I've added 200, 300, 400 and 500 fit curves, but I missclick pressing the red circle zone on the list for the 600 Hz curve, then the 500 Hz fit curve will be added.
My english is not that capable of explaning complexe things, I hope it is understood

Thanks
PS: maybe it is something that can't be fixed, it is just like it is