If Amplitude, the tips from @DickCappels are useful. Also, keep in mind the generator might be calibrated for a 50Ω load on its output, but the oscilloscope typically has 1MΩ of input impedance, which will show as a higher amplitude. Also, it is easy to confuse amplitude with RMS or peak-to-peak - some generators' output levels can be as peak-to-peak and others can be simply amplitude.
If frequency, the oscilloscope might be out of its "cal" position in the horizontal s/div setting.