how to change page break navigation style in word press

This is controlled by your theme. What theme are you using? Where did you download it from?

I am download it form – https://themeforest.net/item/soledad-multiconcept-blogmagazine-wp-theme/12945398
but theme has no option to fix this….

I’m sorry but as you are using a commercial theme, you need to seek support from the theme’s developer/vendor. We do not have access to, nor do we support, commercial products here. Try https://themeforest.net/item/soledad-multiconcept-blogmagazine-wp-theme/12945398/support