I'm just a beginner but this is what I've found to help:

To tackle chord changes, I find it useful to just keep changing between 2 chords very slowly but accurately, then gradually build up speed. Study how your fingers are moving and what finger(s) needs more attention.

Once you have formed the chord you must pick each string to check all the notes sound clear.

When changing chords you can often just slide 1 or more fingers to their new positions.

Another technique is to form the chord on the strings, then lift your hand off, stretch out your fingers and then reform the chord on the strings. So your hand learns the chord shape.

As has been said repetition is the key, but do it slowly so that you are repeating good actions, not sloppy ones. Practice makes permanent (not necessarily perfect). It takes loads of practice, so don't think, it's not working for you.