Improve Ad relevance for an ad group

Hello there, , we have an adgroup which should be performing better than it is.
our ad relevance is "below average".

we would like this ad groups performance to be "average" or "above average" to help us improve quality score.

Please advise on your best course of action and implement changes needed to our ad's to make this better, we only have a handful of ads, one of which has strength of "excellent"