
Pt. Shri. Vedavyasacharya
General
The elders explain this clearly:
If it is worn below the navel, it is said:
“Adho nābhe tapaḥ kṣhayaḥ”
Meaning: the merit of one’s penance (tapas) gets reduced or lost.
Conclusion:
To ensure this, one may adjust or tie the thread properly so that it stays in the correct position.