YOU SAID:

I said hello and they didn't understood

INTO JAPANESE

私は挨拶しましたが、彼らは理解してくれませんでした

BACK INTO ENGLISH

I said hello, but they didn't understand

INTO JAPANESE

私は挨拶したが、彼らは理解してくれなかった

BACK INTO ENGLISH

I said hello but they didn't understand

INTO JAPANESE

挨拶したけど理解してもらえなかった

BACK INTO ENGLISH

I said hello but you didn't understand me

INTO JAPANESE

挨拶したけど理解してくれなかった

BACK INTO ENGLISH

I said hello but you didn't understand me