Horizontally centers the selected objects. If only one object is selected in Draw or Impress, the center of the object is aligned to the horizontal center of the page.
To access this command...
Choose Format - Align - Centered (LibreOffice Writer, LibreOffice Calc).
On Align bar (LibreOffice Impress, LibreOffice Draw), click
Centered
The vertical position of the selected objects is not affected by this command.
To align the individual objects in a group, choose Format - Group - Enter Group to enter the group, select the objects, right-click, and then choose an alignment option.
To align the individual objects in a group, double-click to enter the group, select the objects, right-click, and then choose an alignment option.