Welcome to the forum.
When you look at the results of the PiP in the Program Monitor, you should be able to tell which Preset has been applied, by the position of that PiP footage displaying.
Where does the PiP footage display?
Interesting question. It is helpful to know what Premiere Elements version you are using and on what computer operating system it is running on. In the absence of that information, I will generalize.
Typically, in Premiere Elements 10 when you add an effect to a clip it is shown as an fx listing to the right of the image thumbnail in Edit Header/Effects/Video Effects/and the Effect used.
And, typically you can find a panel for it in the Edit Effects/Properties Palette. When you use Edit Header/Effects/Presets, no such listing is made nor a separate named PiP panel generated in Properties Palette.
The details for Premiere Elements 11 in this regard are similar although interface differences do exist. But in either case, I see two answers to your question (more details if version information supplied):
1. Observe the PiP effect with regard to
a, size 25% versus 40% (relative size will do)
b. the final destination for the PiP effect
c. the action of the PiP effect
With that information, I can type that information into the Search field of PiP area. If I had applied 40% LR Slide In Right
a. Size would be 40%
b. Final destination would be LR (lower right)
c. Action of PiP would be Slide in Right
consequently I would be directed to 40% LR Slide In Right thumbnail
2. The following is a different approach.
a. Create an unnumbered marker above the start of the clip involved. Double click it to open the dialog in which you can type in comments about the clip, including PiP 40% LR Slide In Right. For that matter, you can type in any special effects or comments about the clip that you do not want to forget.