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Firefox 33 will not retain customizzation settings

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  • Last reply by cor-el

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After changing homepage and installing themes, Firefox 33 resorts to default settings on subsequent startup.

After changing homepage and installing themes, Firefox 33 resorts to default settings on subsequent startup.

Chosen solution

If you do not keep changes after a restart or otherwise have problems with preferences, see:

The data of all installed lightweight themes (Personas) and its background color and text color is stored in the lightweightThemes.usedThemes pref in JSON object format ({"id":"#","name":"xxx",...}).


There is software like Advanced SystemCare with its Surfing Protection feature that can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

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Chosen Solution

If you do not keep changes after a restart or otherwise have problems with preferences, see:

The data of all installed lightweight themes (Personas) and its background color and text color is stored in the lightweightThemes.usedThemes pref in JSON object format ({"id":"#","name":"xxx",...}).


There is software like Advanced SystemCare with its Surfing Protection feature that can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.