You can make a dimension longer or shorter, or stretch either of its extension lines. When you stretch the length of a dimension, the dimension value updates automatically to reflect the new length.
To adjust the length of a dimension:
Select the dimension.
Click on one of the lower extension grab handles, then drag the dimension to stretch it. Note that it is possible to stretch the extension line at the same time.
Release your mouse button.
To adjust the length of extension lines:
Select the dimension.
Click the grab handle at the end of the extension line, then drag to stretch the extension line.
Release your mouse button.