On the desktop, under the Advanced Preferences tab, one can change "how Firefox accesses the internet". For my purposes here that means mostly changing the proxy settings. I know that these same settings are available on Android in about:config, and I'm already successfully using those. My problem is how to change them easily, i.e. switch from one proxy to another without editing about:config (and changes to multiple entries are needed for a switch). On the desktop I solve this with separate Firefox profile for each proxy. But the Android Firefox seems to lack the concept of profiles. The Android system profiles are a different thing, aren't they? Anyway, I'm grateful for suggestions how to approach this, wherever they might lead me.