Make sure you're having your activities record on your Strava is as simple as the following steps.
1) Open your Strava App on your phone and select "Record"
2) Once you see that your GPS location has been acquired, you can then select the "change workout" option circled in the below image.
3) Select the workout you are starting from the list and select "Start" when you're ready to go.
4) Pause and finish your activity when you're done with your activity to ensure your information is accurately recorded.