It's a long time since I used PSP5. To change the tool properties try this. Select the Retouch Tool from the side menu. Then Right-click on the hand icon & select Tool Options from the menu. This should open the Tool Options window.

(Toggle the options palette windows with the Tab key.)
If I remember correctly the PSP5 free trial has a time limit of 30 days. Unless you're prepared to purchase PSP I recommend you learn to use one of the freeware alternatives instead.