The word(s) "improve" appears 4 time(s) in 4 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) And come not nigh to the orphan's property, except to improve it, until he attain the age of full strength; give measure and weight with (full) justice;- no burden do We place on any soul, but that which it can bear;- whenever ye speak, speak justly, even if a near relative is concerned; and fulfil the covenant of Allah: thus doth He command you, that ye may remember.

(2) Come not nigh to the orphan's property except to improve it, until he attains the age of full strength; and fulfil (every) engagement, for (every) engagement will be enquired into (on the Day of Reckoning).

(3) But those who believe and work deeds of righteousness, and believe in the (Revelation) sent down to Muhammad - for it is the Truth from their Lord,- He will remove from them their ills and improve their condition.

(4) Soon will He guide them and improve their condition,