LibreOffice 6.1 Help
Vertically centers the selected objects. If only one object is selected in Draw or Impress, the center of the object is aligned to the vertical center of the page.
To access this command...
Choose Format - Alignment - Centered (LibreOffice Writer, LibreOffice Calc)
Choose Modify - Alignment - Centered (objects selected) (LibreOffice Draw)
Open context menu - choose Alignment - Centered (objects selected) (LibreOffice Impress, LibreOffice Draw)
On Align toolbar (LibreOffice Impress, LibreOffice Draw), click
To align the individual objects in a group, choose Format - Group - Enter Group
double-click to enter the group, select the objects, right-click, and then choose an alignment option.