time machine icon color

My icon changed to green when I did a select disk for backup

under preferences. From pluging everything back in and booting up.

It has been yellow for 18 months of use, I thought I

did something wrong.... Found backups just fine after I calmed down.

This brought up a question of yellow or green icon does it matter?

Everyone describes a green icon....mine is in yellow.

I also do not use the backup feature in QuickBooks.

I tell it not to save and I backup with time machine.

The QuickBooks backsup is on my desktop company icon.

Is this okay or should I backup thru QuickBooks.

Thank you