Recent answers to Firefox window size upon launchhttps://support.mozilla.org/en-US/questions/13540672021-10-14T10:05:19-07:00https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved
You may have co2021-10-14T10:05:19-07:00fredmcd-hotmailhttps://support.mozilla.org/en-US/questions/1354067#answer-1451090<p><a href="https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved" rel="nofollow">https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved</a>
You may have corrupt <strong>xulstore.json</strong> file.
</p><p><strong>Close Firefox. </strong> Open your file browser to this hidden location:
</p>
<ul><li> <strong>Mac: </strong> *~/Library/Application Support/Firefox/Profiles
</li><li> <strong>Linux: </strong> *~/.mozilla/firefox/Profiles
</li><li> <strong>Windows: </strong> %AppData%\Mozilla\Firefox\Profiles
</li><li> *C:\Users\&lt;user&gt;\AppData\Roaming\Mozilla\Firefox\Profiles
</li><li> <strong>Windows XP: </strong> C:\Documents and Settings\&lt;user&gt;\Application Data
</li></ul>
<p> \Mozilla\Firefox\Profiles\
</p><p>Search for the above file. Then rename or delete it. Restart Firefox.
</p>