Here is the full list of all 21 Just Find It 3 achievements.
Use Hint 30 times.
Complete All Difference Mode.
Finish 30 Difference Mode Levels.
Finish 10 Difference Mode Levels.
Complete All Detail Mode Levels.
Complete All Match Mode Levels.
Complete All Memory Mode Levels.
Complete All Montage Mode Levels.
Complete All Cycle Mode Levels.
Find 50 Difference.
Use Hint at least 10 times.
Complete All Swap Mode Levels.
Use Hint for the first time.
Play a Cycle Mode without using Hint.
Play a Difference Mode without using Hint.
Find 10 Difference.
Play a Detail Mode without using Hint.
Play a Match Mode without using Hint.
Play a Memory Mode without using Hint.
Play a Montage Mode without using Hint.
Play a Swap Mode without using Hint.