Click on the uMatrix icon.
uMatrix shows a table of domains (the rows), and features (the columns).
The color of the field in the intersection determines if that feature is activated for that domain. Green means activated, red means deactivated.
To activate a feature, click in the upper half of the field to make it green. Click the lower half to make it red (feature deactivated). Click a field twice to make it grey (use inheritance).
Usually subdomains inherit the color of the domain, but if you let uMatrix display subdomains, you can configure them individually. Hover over the field labled "all" to make a tiny arrow appear. Enable display of subdomains by clicking the arrow to make it point down. Disable display of subdomains by making the arrow point up.
If the upper left corner of a field has a different color than the rest, the color of that corner shows the permenently saved state, and the rest of the field shows the current, temporarily modified state. To save the current state permanently, click the lock icon.
The effect of changes to permissions depends on the currently selected scope.
The scope makes it possible to define rules either only for a specific domain, or all domains, or whatever the current domain is when the rules is being applied.
An example for a global rule would be to always allow or always deny the Facebook like button, on all web pages.
If you select the global scope (*) in the upper left, the matrix shows global rules, and all changes that you apply will effect all web pages.
Except changes in the row "current domain", which will be ...
If you select the current domain, then matrix shows the effect of inheritance (from domains to subdomains, and the rules for current domain), and you can set rules which will be applied in the future only when you are again on that same domain.
Click on the upper left...
Why does the color of domain-fields change when the other scope is selected?!?
edit the rules to make them contain * * * block * 1st-party * inherit * 1st-party cookie allow * 1st-party css allow * 1st-party image allow
How can this be achieved in the UI, without manually editing the config?
HTTP Switchboard Wiki