Most of the time I recite the quran I can't focus on it. sometimes I change the kasra,dhamma or fatha and sometimes I change the word. The word is mu'minun I recite it mu'minin.How to get rid of this problem.Sometimes I'm seeing the word is mu'minun but I'm pronouncing it mu'minin.I practice a surah many times sometimes I recite correctly but next time I recite something wrong.Please give me solution.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The solution to the problem that you are suffering from lies – after seeking the help of Allah Almighty – in two matters:

The first: To learn the recitation of the Quran on the hands of a skilled Shaykh who will correct for you the mistakes that you make and the words that you mispronounce.

The second: To strive to be attentive with your heart when reciting and focus on the words that you are reading, because distraction of the mind is a cause of error when reciting.

May Allah enable you to do acts of goodness.

Allah knows best.