Right-click on the "Sheet-Metal1" (name may vary) feature in the feature manager tree and select "Edit Definition" This is where the default bend radius is defined.
If you double-click the "Sheet-Metal1" feature, the default radius will appear in the model window for editing. It is also possible to link the dimension to part thickness so that the radius matches thickness as thickness changes.
Due to illness, the part of The Tick will be played by... The Tick.