How to underline-only when annotating in Apple Books.

I found the answer yo the question myself—something that has become necessary in latter day Apple world (it’s been a long time since support was worth anything, 20-30 years).

First phase:

Highlight text, then underline it so you have yellow + underlined text.

Highlight part of the same text again and extend to new text and highlight yellow, then close Highlight window (not the document—just the highlight).

Then highlight the text again, and click "remove" from the options. This leaves the text underlined only.

Second phase:

Highlight only a part of underline-only text. Exit HL window.

Highlight a part of the yellow only highlighted text, then underline — all the text will become underlined. Window automatically closes.

Highlight a part of the Y + U text and extend to new text.

The new text will be underlined only.

From thence forward, any highlighting will be only underlined text. Closing the document resets the original yellow.

if there’s an easier way to do this, I’d like to know — workarounds like this are a bit annoying.