for most, foremost

For most or for most ( two words ) means suiting the purposes of a majority, or of the greatest number or quantity--
This is the best product for most household uses.
For most may also mean with regard or respect to a majority--
For most people, losing things is a fact of life.

Foremost or foremost ( one word ) means first in order of rank or order; the best known or respected--
He is the world's foremost authority on the subject.
She is one of the foremost technical specialists.

Now that you know that, you can say--
"For most viewers, a recommendation by the foremost authority is very convincing."

Note-- "four most" ( two words )  means 4 objects, places, or persons with the majority or greatest quantity--
That is one of his four most favorite movies.
The four most popular candidates will run in the November election.