This feature is available in Ultimate edition only.
Option 1. In the Portfolio Tree Grid
From the main menu, select Portfolio Planning > Portfolio Tree.
Customize the grid by adding the Strategic Themes column.
Double-click on the Strategic Themes column heading to make it editable.
Select or search for the strategic theme(s) you want to assign and click Save. Note that you can assign multiple strategic themes to a portfolio item.
Option 2. On the Portfolio Item Details page
Open the Details page of a portfolio item and select one or more strategic themes in the Strategic Themes field.
The Strategic Themes presented in the list are those that exist in the portfolio item's project or parent projects. It is possible to assign a strategic theme outside of that segment of the project tree by using the search. Just start typing the title of the strategic theme in the selection box and you'll see matches from throughout the system.