The Stryd platform will calculate your critical power automatically based on your running data. Critical power is the power you can hold for about 50 minutes (~10k distance for most).
Auto-CP is recalculated each time a run is uploaded into our data store. Your CP will only increase if you run at a higher power level for a certain time than you did in the last three months for the same time interval. After three months, your runs are no longer considered when calculating CP.
For example, I ran a 5k race in 20 minutes on the 1st of October. Any 20-minute effort after my race will likely be ignored until January since I am unlikely to run at race power in my regular training.
If you feel your auto CP is incorrect, you can reset your auto CP calculation and start anew (it will take 3 runs for the system to give you a new CP number).
If you need additional assistance, contact firstname.lastname@example.org.