Does glow adjust DPO based on bbt?

I saw that glow now has xdpo on the bbt chart.  Does this change depending on the temps you put in? Or is it set based on previous cycle data? Does it change if putting in opk results? I'm just curious because after inputing my data into fertility friend it is showing my ovulation date as cd13. Glow is showing cd16. I didn't do opk this month so I was wondering what the predictions were based off of.