Billy, you really need to get a handle on Oscilloscope Basics. The Oscilloscope is a tool and unless you sit down and learn how to use that tool and what the tool is capable of you will never benefit from its use. Nobody here using an online forum can teach you how to use a scope, not completely anyway. Triggering on a scope is just one of many features with sub features, Internal, External, Coupling, Slope and Source with the list going on and on.
As to measuring the phase shift or phase difference between two signals? Since you mention 400 Hz we can look at 400 Hz. You have two 400 Hz signals so you can for example connect one 400 Hz signal to the CH 1 vertical input and the other to the CH2 vertical input. If CH 1 is your reference signal then set the scope to trigger off the CH 1 vertical input and set up channel 1 for a nice stable display. Let's see, by my math the time for a 400 Hz sine wave is 2.5 mS (0.0025 Second) so a sweep time setting of 1 mS / Div should be convenient and show a few repetitions of the signal, actually about 4 repetitions. If you use .5 mS / Div with 10 horizontal divisions the full sweep would be 5 mS and display two repetitions of your 400 Hz sine wave.
With triggering set for Channel 1 obtain a stable display. Set both vertical input couplings to GND and adjust the vertical positioning so both traces (CH 1 & CH 2) overlap. Next you return the vertical input coupling to AC. Using the vertical gain adjustments adjust the gain so both traces of your 400 Hz. are the same amplitude. You now have two 400 Hz. signals of the same amplitude overlapped on the screen. They should be stable with good triggering. Matters not where on the channel one signal triggering is happening. Hell if it makes you feel better then set the triggering for internal, CH 1, + Slope and adjust the level so the signal triggers on the + Slope right at zero crossover. It doesn't matter!
Now we know the time for one repetition of 400 Hz. is 2.5 mS. We also know that one repetition of our signal is 360 Degrees. Therefore 2.5 mS / 360 = .0000069 S or each degree = 6.9 uS of horizontal time.
OK, so look at a point on Channel 1 where one of the 400 Hz waveforms crosses the vertical center line. Work across to where the Channel 2 signal crosses the vertical center line. Measure the time between the leading edge CH1 point and the leading edge CH 2 point. Then divide that number by 6.9 uS. Lets say that CH1 leads CH2 by 69 uS. then you get 69 / 6.9 = 10 Degrees. So using channel 1 as the reference we can say channel 1 leads channel 2 by 10 degrees.
Don't want to use time? Cool and no problem. Count the minor divisions horizontally for one repetition of CH1 signal. You know 400 Hz. is 2.5 mS so if the time base is set for .5 mS / Div one repetition of 400 Hz should be 4 divisions and at 5 minor divisions horizontally per division that would be 20 minor divisions. OK so now 20 minor divisions equal 360 degrees so 360 / 20 = 18 degrees per minor division.
Now just as before measure from a point on the channel 1 signal (again a zero cross over is convenient) to the same point on the channel 2 waveform. How many minor divisions? Multiply the number of minor divisions by 18.
Ron
As to measuring the phase shift or phase difference between two signals? Since you mention 400 Hz we can look at 400 Hz. You have two 400 Hz signals so you can for example connect one 400 Hz signal to the CH 1 vertical input and the other to the CH2 vertical input. If CH 1 is your reference signal then set the scope to trigger off the CH 1 vertical input and set up channel 1 for a nice stable display. Let's see, by my math the time for a 400 Hz sine wave is 2.5 mS (0.0025 Second) so a sweep time setting of 1 mS / Div should be convenient and show a few repetitions of the signal, actually about 4 repetitions. If you use .5 mS / Div with 10 horizontal divisions the full sweep would be 5 mS and display two repetitions of your 400 Hz sine wave.
With triggering set for Channel 1 obtain a stable display. Set both vertical input couplings to GND and adjust the vertical positioning so both traces (CH 1 & CH 2) overlap. Next you return the vertical input coupling to AC. Using the vertical gain adjustments adjust the gain so both traces of your 400 Hz. are the same amplitude. You now have two 400 Hz. signals of the same amplitude overlapped on the screen. They should be stable with good triggering. Matters not where on the channel one signal triggering is happening. Hell if it makes you feel better then set the triggering for internal, CH 1, + Slope and adjust the level so the signal triggers on the + Slope right at zero crossover. It doesn't matter!
Now we know the time for one repetition of 400 Hz. is 2.5 mS. We also know that one repetition of our signal is 360 Degrees. Therefore 2.5 mS / 360 = .0000069 S or each degree = 6.9 uS of horizontal time.
OK, so look at a point on Channel 1 where one of the 400 Hz waveforms crosses the vertical center line. Work across to where the Channel 2 signal crosses the vertical center line. Measure the time between the leading edge CH1 point and the leading edge CH 2 point. Then divide that number by 6.9 uS. Lets say that CH1 leads CH2 by 69 uS. then you get 69 / 6.9 = 10 Degrees. So using channel 1 as the reference we can say channel 1 leads channel 2 by 10 degrees.
Don't want to use time? Cool and no problem. Count the minor divisions horizontally for one repetition of CH1 signal. You know 400 Hz. is 2.5 mS so if the time base is set for .5 mS / Div one repetition of 400 Hz should be 4 divisions and at 5 minor divisions horizontally per division that would be 20 minor divisions. OK so now 20 minor divisions equal 360 degrees so 360 / 20 = 18 degrees per minor division.
Now just as before measure from a point on the channel 1 signal (again a zero cross over is convenient) to the same point on the channel 2 waveform. How many minor divisions? Multiply the number of minor divisions by 18.
Ron