The subdialog for editing pattern colors can be used to modify the selected pattern:
The new pattern size can be given in percent or in a discrete unit like pixel or inch. Besides it is possible to rotate the pattern with Rotation and to skew it with Shearing. Both values are degrees.
Tip: In the Layer Properties dialog there is the setting "Align Pattern" (see chapter 7.5.48). If this setting is activated, the pattern is always aligned to the origin of its layer and transformed accordingly.