Select the line or block you would like to modify by single-clicking it. You can select multiple lines or blocks by holding Shift and selecting. Note: Line style can only be applied to a line and block style to a block.
Click "Edit" in the Menu bar and select either "Copy Block Style" or "Copy Line Style" depending on what object is selected.
Select the existing object with the formatting you want to copy.
The formatting will instantly be applied to the selected object(s).