If you just want to transpose one track one octave it is easier to select all the steps (zoom out so in step mode all steps are on one page) and transpose up or down an octave with the second encoder. Hold Rec to select them all at once.
When using the master transpose track, select love mode and hit a key. All tracks with transpose enabled will follow.
So transpose track ( track 16 in your case) has zero transposition at C4.
So if you want one octave lower, play on
Live mode or sequence C3.
Playing/sequence C4 will put you back to un-transposed.