ineuw,
On reading your latest posts I was wondering if you are remembering to
only launch Firefox Portable using the launcher program which would be at (somewhere like):
W:\FirefoxPortable\FirefoxPortable.exe -- you can create and a use a normal shortcut to do that if you want. The launcher passes on the path that Firefox is being run from to firefox.exe so that firefox.exe knows where to look for its data (
i.e. firefox.exe will look for its files inside the portable folders and not elsewhere). Also the launcher determines the bit-ness of the firefox.exe to launch, 32-bit or 64-bit. I think the launcher also reads and enacts the information in the FirefoxPortable.ini file you modified.
Going forward, you should be aware that if you want to update your FirefoxPortable installation you should only do so by downloading and 'installing' the FirefoxPortable package from here:
https://portableapps.com/apps/internet/firefox_portable This is a recurring theme at PortableApps forum with people asking if it is possible to allow FirefoxPortable to just install updates, offered by Mozilla, from within the running Firefox program. The developers at PortableApps say that this can be done but with the caveat that in some instances it might break or adversely affect FirefoxPortable. So their bottom-line advice is only to update using an official release from PortableApps -- this should ensure that you don't run into problems. In any case, definitely turn off the auto-update feature in your FirefoxPortable.
Lastly, to do the update do the following:
1) Download the FirefoxPortable package installer.
2) Run it and point its installation path to the folder that contains your existing FirefoxPortable installation
e.g. W:\FirefoxPortable Once you've done that you can Okay the installation.
OS: Windows 10 Pro. x64