Automatic positioning is enabled by default and lets the system position the nodes. Click the ‘magnet’ icon to disable it and position manually
Pin node to position
In automatic mode, to pin the position of a node, click on the node to open the node popover and click on the little pin symbol (top-right of the modal window)
Manual positioning is enabled when automatic positioning is disabled, and allows to drag nodes around. All stored positions are lost again when automatic positioning is enabled again.