How to avoid the Grand thumb

Something my father showed me years ago https://www.youtube.com/channel/UC6aiAmjvMfLbbbZ3_rK0B4w/join https://patreon.com/Thekoba49?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=creatorshare_creator&utm_content=join_link ... https://www.youtube.com/watch?v=jt9DnGGoRCQ