Underline Text Feature

Hi
I launched this ticket back in May. Although I got an answer and a proposal for solution (= installing Plugin https://wordpress.org/plugins/re-add-underline-justify/), it still does not work?

Installing this plugin has NOT brought back the “underline feature”.

Can you please help me.
The “underline” button is missing for underlining text? I have “bold” and “italic” but no underline?

thx alot, Charles