Altering Slider Text in Sight Theme

Hello. In the “Sight” theme, the text shown in the carousel slider is automatically drawn from the beginning of the post in question. Is there a way to change this so that the slider text does not match the beginning of the post? I would like to give a one-sentence description of the posts rather than show how they start.

I don’t know coding (I should learn, I know), so I’m not able to do things like creating child themes. A plugin or something like that would be ideal.

Thanks!