Adobe Acrobat is Not Saving Tool Pane Preferences

The sidebar tool pane keeps appearing when I open a PDF even though I have:

• Went to Edit > Preferences > Documents and selected "Remember last stare of the All tool panes when opening documents."
• Reset preferences and tried to select the "remember" option again.
• Ensured I have the latest version of Adobe Acrobat.

Any advice on how to permanently hide the sidebar tool pan would be greatly appreciated. Thanks.