The current UI text states:

The default is three subfields. More subfields enables more specific queries, but increases index size.

The text should be:

The default is three subfields. More subfields enable more specific queries but increase index size.

Note the changes in the second sentence:

• enables -> enable (Subject-verb agreement)
• , but -> but (Comma misuse. Commas aren't needed to separate a clause without a subject.)
• increases -> increase (Subject-verb agreement)

CC @gchaps @KOTungseth