Tutorial issue: playhead as IN/OUT to replace clips

I'm following the DaVinci Resolve 16 Beginners guide PDF and on lesson 4, page 110, there's a topic called "Replacing a shot". If I interpreted the instructions correctly, the shot from my source view should use its "playhead"(jog bar) as an IN point and replace my timeline's shot from the timeline's playhead onwards.

But the source view is replacing the entire timeline clip with the entire source view clip. The playheads are not functioning as IN/OUT replacement points.

If I'm mistaken about this and you can only replace entire clips, not just parts of them using the playhead, then why does the tutorial says this on page 112, step 5:

"Move the playhead roughly one-third of the way into the 04_JET_LANDING_2 clip.
Around the time when you first see the jet engines enter the frame."

"This is the time location when you want the plane to come into the frame on the
10_MALDIVES shot."

"In the source viewer, drag the jog bar until you first see the plane coming into frame."

"With the playheads aligned, you can use the replace edit button in the toolbar."

It REALLY makes it seems like you can exchange clip parts by just using the playheads.

Works as expected on my Resolve 16 Mac system. Perhaps you can make a screen capture and post a link to it so we can see what you are doing?

I also had no issues doing this.

If I interpreted the instructions correctly...

Maybe look there?

Replace (F11) works just like that: replaces the entire timeline clip with the source clip with the current source frame landing on the current timeline frame. Very useful and powerful function though often misunderstood and underused.