Q: How can I change the default beam grouping in Sibelius? Specifically, I would like to have the 8ths in the time signature 4/4 be displayed in groups of 2 instead of 4.
A: Option 1:
Change the default beam grouping for a certain passage: select the passage and select Beam Groups in the Reset Notes group of the Appearance tab.
In the following dialog you can now change the preset from 4,4 for the 8ths to 2,2,2,2.
Choose the default beam grouping when creating a time signature: select More Options at the bottom of the Time Signature gallery.
In the subsequent dialog, after having chosen the time signature, select Beam and Rest Groups…
Now you are shown the dialog Reset Beam Groups, where you can choose the grouping you would like to have as a preset.
A German version of this post („Balken neu gruppieren”) is available here.