If you have a Bible and commentary (or any resource with a Bible index) open and they are not linked and you want the commentary to sync to the current reference in your Bible, then click in the Bible's reference box. It should turn blue. Then copy it, in windows hit Ctrl and c at the same time. Then click in the commentary's reference box and it should turn blue. Then paste, Ctrl and v and hit enter or the blue arrow. If it is a commentary series, it should sync even if the commentary volume is from a different book of the Bible.
"For the kingdom of God does not consist in words but in power" Wiki Table of Contents
Wiki => Getting Started with Logos includes:
Tip: PC control key often becomes command key on Mac.
Another option is prioritizing a commentary in Top 5 Bibles so can right click on a Bible reference, click reference, click commentary, which opens commentary to desired verse reference. When commentary has focus, can click "+" to open another commentary to same verse (albeit some commentaries do not comment on every verse so they open near desired verse).
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Logos Wiki Getting Started Logos 4 Beta