I use Vegas Pro 15 and when I snip audio tracks then both of the new parts of the audio get muted at the seam. Is this something that can be turned off (and if so the how?) or is it unchangeable?
https://cdn.discordapp.com/attachments/430406009748455434/681567608147148813/unknown.png
That's done by default to stop audible clicks from happening at audio edits. Without that quick fade, sudden changes in the waveform at edit points are so abrupt they sound like a "click" in your audio.
To answer your question, yes, you may turn it off and change Vegas' default behavior:
Options>Preferences>"Editing" tab>Quick fade for audio events (ms):
The normal default is 10. Change that number to 0 to remove the quick fades from that point forward.
I usually lengthen one or both clips very slightly so there is a few milliseconds of crossfade rather than the "mute"
Leave it alone and worry about something else. @Turd is correct about the setting and the rationale for having it, however, it can't be set to less than 1 ms, so you'll always see a fade. As wjauch said, a little overlap never hurt anything. On occasion, I split within a clip and I just drag the fades back to their original states since there is no mismatch in the audio from sample to sample. If I'm awake when I do the split and the audio continues while I do something else with the video, I only split the video and leave the audio unchanged.