First recorded (as “Hier Encore”) by Charles Aznavour (1964).
Hit English-language version by Roy Clark (US #19/C&W #9/MOR #6/CAN #7 1969).
From the wiki: “‘Yesterday, When I Was Young’ was originally written and recorded as ‘Hier Encore’ (‘Yesterday Again’) in France by songwriter Charles Aznavour and released in September 1964. It was subsequently released in Italian as ‘Ieri Si’, in Danish as ‘Hvor tiden går’, in Japanese ‘帰り来ぬ青春’ [‘Returning Youth’], in Spanish as ‘Ayer Aún’, ‘Eilen kun mä tiennyt en’ in Finnish and, in 1969, in English as ‘Yesterday, When I Was Young’. It is considered one of Aznavour’s greatest hits.
“The English-language lyrics, written by Herbert Kretzmer, tell of a man reflecting on his life. Country singer Roy Clark covered ‘Yesterday, When I Was Young’ in 1969. His version became his biggest hit up to that time on the Billboard Hot Country Singles chart, peaking at #9 and becoming his only Top-40 pop hit, peaking at #19. Clark performed the song at Mickey Mantle’s funeral in 1995, at Mantle’s personal request.”
Roy Clark, “Yesterday, When I Was Young” (1969):