The Prophet ﷺ told Mu'adh bin Jabal (RA) to say this dua after every prayer -
اَللَّهُمَّ أَعِنِّيْ عَلَى ذِكْرِكَ وَشُكْرِكَ وَحُسْنِ عِبَادَتِكَ
Transliteration
Allaahumma 'a'innee 'alaa thikrika, wa shukrika, wahusni 'ibaadatik
Translation
O Allah, help me to remember You, to give You thanks, and to perform Your worship in the best manner.
The Prophet ﷺ held Muadh's hand and taught him this. Say it after each fard prayer. It asks Allah to give you power to remember Him, say thanks, and pray well.
Say it right after salam. The Prophet ﷺ said to read it at the end of every fard prayer when you need help in worship.
The Prophet ﷺ held Muadh bin Jabal's hand. He said I love you. Then he taught him this dua to say after each prayer.
It means O Allah help me remember You. You are asking for power to worship in the best and most beautiful way.
No. The right word is a'inni, not inni. A'inni means help me. This masnoon dua makes your daily salah perfect.
It keeps you humble. Even the power to thank Allah and pray - that's a gift from Him alone. This dua reminds you of that.