You can change a dimension’s line, arrow and text style by applying a different dimension style to it, or by editing dimension style properties.
To change the style of a dimension:
Select the dimension. You can select multiple dimensions using Shift+click.
Right-click and select Properties, or select Edit > Modify Elements > Properties.
In the Dimension Styles dialog, select the style you want to apply to the dimension.
To create a new dimension style,
click the Add Item button, then type a name for the style and press ENTER.
To edit the properties of the currently selected dimension style, click Edit, then make your changes in the Edit Dimension Styles dialog. See Dimension Style Properties.
With the desired style selected, click Set Current.
Click OK.
Note: Dimension styles that are edited or added through inserted dimensions are saved with the current project only. If you want to save them in the dimension styles library, so that they can be made available in other projects, see Saving Dimension Styles to the Library File.