Is this question related to Photoshop Mix (mobile app)? Or, are you really using Photoshop? Please let me know and I’ll move the post if needed.
In Photoshop, when you merge layers they become rasteried and you can no longer edit the text.
Photoshop Mix. Thank you
I apologize for the delay in response.
I believe you're using an iOS device for the PS Mix app and once you merge the layers you can do the editing on that current layer. you won't be able to separately move onto the unmerged layer for editing.