I am having the same issue with the version 2015.006.30033 of Adobe Acrobat where I am unable to permanently close tools pane. My Adobe does not save my hide tool pane setting when I hide it and open other PDFs subsequently. I checked with my IT group and they suggested that I already have the most updated version available to us.
I also do not have the option to select/deselect the check box in Edit--Preferences--Documents to save my default.
I have the other posts on this topic and cannot find a solution that works for me at this time.
Thank you in advance.
As per the issue description mentioned above, you are unable to close tools pane permanently in Acrobat, is that correct?
Could you try updating Acrobat to the latest patch - 2015.006.30418 using this link: DC Release Notes — Release Notes for Acrobat DC Products rebooting the machine after installing update and check if that works.
Let us know if you need any help.