usevinyl2.png
You can upload captures of your screen as attachments to your posts.
Please upload the following:
1. Overall interface, while having the cursor on top of a wave in the deck (the part as in my capture uploaded earlier today)
2. Preferences > Audio window
3. Preferences > Vinyl/CD window
The A and B you mean are in the mixer section in between the decks. There you can select the input for the mixer section (Deck or vinyl). Please be aware that this is for vinyl audio usage and not for time code.
In the image below I combined the capture for suggestions of Jaymarkus and mine.
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