When you collect data using errorless teaching, each time you press + it records success with no prompts at all and changes the default prompt to Independent.
Let's say you're on trial 4/10 and the prompt shows as independent. If trial 5 requires a prompt, tap P to bring up the full prompt list. When you choose one, a minus is recorded and the prompt you chose will show up as the default.
If trial 6 requires the very same prompt, tap the P quickly. Again, a minus is recorded and your previous prompt is retained. If it requires a different prompt, long-tap the P and select your new prompt level from the list. If it requires no prompt, simply tap the plus and your default will go back to Independent.
Later when you visit the chart, tap the data point to see details. You might see 6/10 in the heading; tap that heading to see each trial with + - or P along with the type of prompt for the P's.