Originally Posted By: artie505
For what it's worth, my update procedure, done while I"m on line, is:
  1. Copy new version from .dmg.
  2. Paste it over my existing earlier version (which is stored in my data partition).
  3. Launch new version.
  4. Click to OK download.
and that procedure perpetuated my prefs, etc.

I added another edit to my previous one.

I don't understand your update procedure.
• What does it mean to copy new version from .dmg? [I just open the Firefox 67.0.dmg file (as I've always done previously without any weirdness intervening).]
• Your step #2 is completely opaque (incomprehensible) to me.
• Steps #3 and #4 likewise.
Given your own concerns about the procedure, I doubt if I could be persuaded to follow such (even if I understood it).