There are a few potential causes of low CTR:
1) Your ad copy isn't relevant to your target audience - make sure your ad copy is relevant to what you're selling and who you're selling it to.
2) Your ad is not being served to the right people - make sure your targeting is accurate and that you're not targeting too broadly.
3) Your ad is not being served often enough - make sure your ad budget is sufficient to reach your target audience.
4) Your ad creative is not compelling - make sure your ad creative is eye-catching and relevant to your target audience.
If you're still having trouble troubleshooting your CTR issues, consider hiring a professional to help you optimize your ad campaigns.