Firefox portable update problem

If I use Firefox portable on mobile.de I see no pics. This I got on an update. Now I try to use the old Version. I have found an old copy
that I am using on C:\FirefoxPortable\. To get no Update message I have created a fiele policies.json and saved it in the folder
C:\FirefoxPortable\App\distribution
the contend is:
{
"policies": {
"AppAutoUpdate": false
}
}
This works, I do not get a Update message.

But some starts later I get the message like this You got an Umdate to the lates version.
And I do not see any pics on mobile.de. Yes!

Renaming my FirefoxPortable folder helps to get the old version, but how long?
Thanks in advance