There are several ways to change the text size of PMI dimensions and annotations.
Change all PMI elements and associated graphics (lines, leaders, and arrows) at once, using either of the following methods:
Automatically scale elements. When you use the active model style to determine text size, PMI elements scale automatically as the view is zoomed in and out. This sometimes results in PMI being too large or too small relative to the feature or component.
Change element size interactively. You can use the Increase PMI Font and Decrease PMI Font buttons to change the size of PMI elements based on pixel size. This has the advantage of letting you fine-tune the size interactively.
Change the size of new elements by editing the style. You can set a default text size for all new PMI elements on the Text page of the Modify Dimension Style dialog box. You can access this dialog box using the Styles command 
.
Change the size of individual PMI elements. You can override the default text size for individually selected elements using the Properties command.
You can specify the break line length and the gap between the break line and the PMI text on the Lines and Coordinates tab in the dimension style and in the dimension properties.
To learn how to set and change PMI text size, see the Help topic, Change PMI text size.
PMI dimension color is an at-a-glance indicator as to whether a dimension is locked or unlocked. You can change the global color setting for PMI dimensions. This also changes the color of PMI annotations.
You can change global PMI color settings on the Colors page of the Solid Edge Options dialog box.
The default color of unlocked PMI dimensions is blue. It is the same as that set for all sketch elements. You can choose another color for them from the Sketch list.
The default color of locked PMI dimensions is red. It is the same as that set for handle elements. You can choose another color for them from the Handle list.
You cannot change the color of individual PMI elements.