Hi again my friend,
have you downloaded all the manuals of the DGX 670?
https://europe.yamaha.com/en/products/musical_instruments/pianos/portable_grand/dgx-670/downloads.html#product-tabsIt should be there somewhere something to press or to "tick" for that function to work as it does on a PSR
Automatically Changing One Touch Settings with the Main Sections (OTS Link)
One Touch Setting (OTS) is a convenient feature that automatically calls up the most appropriate
panel settings (Voices or effects, etc.) for the currently selected Style. When the [OTS LINK] button
is turned on, pressing a different MAIN VARIATION button (A − D) automatically calls up a One
Touch Setting appropriate for the selected Main section.
NOTE
• You can call up the information window to confirm which Voices are prepared for each Main section (A − D) of the current Style by
pressing the [6D] (Info) button. If the button is not shown, press the [8D] (Close) button to call it up. Gray color for a Voice name
indicates that the corresponding part is currently turned off.
• When using the Adaptive Style function (page 51), the OTS is not called up when the Main sections are changed automatically,
even if the [OTS LINK] button is turned on.
• When you change the Voice after the OTS is called up, or when the Main section is changed without pressing any MAIN
VARIATION buttons (such as when using the Adaptive Style function), you can recall the previous OTS by turning the [OTS LINK]
button off and turning it on again.
Adding