there was a thread about a year ago,.
try doing a search as there were a lot of good tips.
Depending on what you want to achieve settings can very significantly.
https://www.pentaxforums.com/forums/general-photography/80702-please-help-tak...-pictures.html
I also posted the following in the post your photos section
some of the issues involve whether you want only a starburst, or if you want to see the vertical trail of the firework as well as a burst, and whether the burst should be streaks of light or sharper points of light as in my shot.
Also, post processing comes into play here, by adjusting the level considered black, so that you can eliminate the smoke and only highlight the starburst.
Lots to review, then ask away