Hi Melissa, there are a few different reasons that tab might reappear at startup:

(1) It is set as one of your home pages (2) Firefox is restoring your previous session, but keeps restoring an older one instead of the latest one (3) One of your add-ons opens it (4) The desktop or Taskbar shortcut you use to start Firefox has been modified to open it (5) External malware or a scheduled task triggers when you start Firefox

To check on #1, see: How to set the home page.

To check on #4:

• Right-click your Desktop shortcut and click Properties, or
• Right-click your pinned Taskbar button, then right-click Firefox, then click Properties

Windows should show the Shortcut tab automatically but, if not, click Shortcut.

Then check the Target. On 64-bit Windows, it's usually

"C:\Program Files\Mozilla Firefox\firefox.exe"

so anything after that is questionable.

Were you able to track it down so far?

THANK YOU! I used the Menu Bar on the right and with the link you provided was able to use Settings to reset my Home Page using Custom URLs to be what I need. THANK YOU!!!!!