These phrases tell why people should praise Yahweh. Alternate translation: "because he has taken pleasure in you and placed you on his throne" (See: [[rc://en/ta/man/translate/figs-distinguish]])
The idea of being on Yahweh's throne represents having the authority to rule as Yahweh does. Being king "for Yahweh" means to represent Yahweh as king. Alternate translation: "who gave you authority to rule as he does, to represent Yahweh your God as king" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Possible meanings are 1) "establish" represents helping them in general. Alternate translation: "in order to help them forever" or 2) "establish" represents making them strong as a nation. Alternate translation: "in order to make them a nation forever" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The abstract nouns "justice" and "righteousness" can be expressed with the words "fairly" and "righteously." Alternate translation: "for you to rule fairly and righteously" or "for you to do what is just and right" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])