There must be no slack anywhere in your cast, and when you commence the
cast, the rod tip should be almost touching the water ( or ground).

Having seen you cast, I suspect you are overpowering. Go back to the basic
cast, as described above, and follow it from there. It is easier to have a
good caster watch you, and tell you what you are doing, but you can do it
yourself if you go slowly and take a lot of care.

Ingrained problems are very much harder to eradicate than teaching somebody
from scratch. The first step towards doing so, is learning to recognise the
fault.

Your description by the way, is the classic description of a tailing loop
fault.

TL
MC