Adding subtitles to your Instagram posts is important because it can help increase your engagement, reach, and sales. Consider creating more captivating content. If you have the ability to record a video or have someone else record it, do it. If not, take a video of yourself talking about your product and have it transcribed. You can use one of the transcript services to get it done fairly quickly. The transcript will link back to your Instagram post and make it clear what you are trying to sell. You can use your caption to ask questions and get people to engage with you.