I have the default set to the size I require (11pt from the pre set 18pt) and it works fine with a text box but whenever I add a dimension line it goes back to the originally pre set 18pt.
I have modified the default in the styles defaults but when I add a dimension line and the properties box comes into view the character text/font area still says 18pt. Any help would be much appreciated.
I suggest you choose Hierarchical from the bottom menu is the styles side pane. In this view, you see the inheritance chain between styles.
Draw is less organised style-wise than Writer. One of the problem is there are 3 roots for styles (contrary to Writer where Default Paragraph Style is the ancestor of all styles): Default Drawing Style, Graphic and Text.
Dimension lines are styled Arrow Line which inherit from Lines which inherit from Graphic.
Therefore, customising Default Drawing Style (default for shapes) has no effect on dimension lines.
Customise Arrow Line to fix the issue.
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Thank you - customising arrow line fixed the issue.