Have you read
<https://support.mozilla.com/kb/Firefox+has+just+updated+tab+shows+each+time+you+start+Firefox>?
That looks like the problem you are having.
In any case, this is a developer newsgroup, not a support newsgroup; so
this isn't the place to ask. Try searching on
<https://support.mozilla.com/>; and if you don't find a solution,
there's a forum and live chat (as well as other support venues) listed
at <https://support.mozilla.com/kb/Ask+a+question>.