I'm making a podcast and trying to insert a short separate audio clip with me asking a question into another recording (with the interviewee answering to my questions). How do I do it?
Depends. Are you working in Waveform view or Multitrack? The answer is completely different...
Multitrack. With a razor tool?
No, not with the razor tool! The easiest way is to insert some silence into the timeline. Select the Time Selection tool. Put the cursor where you want your insert to start, and go to Edit>Insert>Silence, and you'll be asked how much silence you want to insert. Put a value slightly higher than you need. This will add time to your session, creating a gap in the timeline with nothing in it. Insert your clip in the gap, butted up to where the answer you want to use is. You'll now have a short gap at the start, which you select, highlighting it. You get rid of this selection using Edit>Ripple Delete and select the 'all tracks' option. This will close it up.
There is another method too. You could swipe all of the material on all of the tracks after where you want your insert to be, group them all and move them along the timeline, for instance. This can be quite useful if you don't want to shift everything - for instance, leaving a music bed in place. Then you'd swipe everything except the music bed and shift it, leaving the music bed alone.