The right video editing software tools can make all the difference. Here are a few simple steps, using the video editing program Adobe Premiere Pro as the example:

1. Import the Instagram video clip you want to add voiceover to.
2. Add an auto track by clicking the timeline header and choosing Add Tracks.
3. Make sure your microphone is prepared.
4. Click Audio Panel, then Audio Track Mixer, and then find the track you’ll add your voiceover to and click R to enable recording.
5. Place the playhead where you want to start the recording. Then right-click and choose Voice-Over Record Setting and then click Record.
6. Complete the recording by clicking the Stop Recording button or the space bar.