Why is it when I'm not signed in to my Firefox accounts on both my laptop computers do my Icon change from say Facebook icon to world Globe Icon.

Why is it when I'm not signed in to my Firefox accounts on both my laptop computers or syncing is turned off, do my Icons change from say Facebook icon to world Globe Icon (Default). Computer 1 has Facebook Icon(Water Landscape) Computer 2 has the World Globe for Facebook Icon. (M&M Candy) When I delete World Globe Icon on #2 and replace it with Facebook Icon, it switches my Icon on #1 to the World Globe Icon. Also, it changes the alignment of my Icons on my desktop as well, rearranges them, put it in a different spots. This has never happened before for over 8 years, now all of a sudden, here we go and I am not sure how to stop this.