I have some bacopa stems in my tank. They keep floating up. How can I plant them so that they dont float up?

Hi, I'm pretty new to this forum and planted tanks. I have a 2.5g tank with Amazon Swords, Micro Swords, and some Java Moss tied to a piece of driftwood. The Amazons are shading a spot on the driftwood that would be perfect for Anubias. However, I'm very reluctant to take the driftwood out in...