Translation:When we decided to have fun, we went to a bar.
How would be a sentence "When YOU/SHE decided to have fun, we went to a bar." translated in Turkish?
same but normally you would use sen or o in the beginning of the sentence, otherwise as the verb "gittik" is conjugated for "we", everyone would assume the first part refers to "we" as well.
"O eğlenmeye karar verince bara gittik." / " Sen eğlenmeye karar verince bara gittik."
For you: (sen) eğlenmeye karar verince, (biz) bara gittik.
For he/she/it: (o) eğlenmeye karar verince, (biz) bara gittik.
They're the same unless you include the personal pronouns.
Sorry, but instead of commenting that the suggestions are not very good you could suggest something better.