You have several text editing and customization options in Social Studio. All text editing is done in the editor, so the first step in text editing is to open a project.
When you open a project, you will see a panel at the left of the editor screen with three main options: "Editor, Video and Music". You should see that the Editor button is highlighted by default.
You can tap the preview (play) icon at bottom left at any time to preview your project. Preview is live and won't create any changes or redirect you away from the editor, so you can make changes and instantly preview them.
Copy editing (changing the words in a text layer) is very intuitive. To edit copy, hover over a text layer in the timeline at bottom and click the “Edit” button that appears. Once you’re clicked, you can type your changes using your keyboard. You can write up to six lines of copy in each text layer and can use up to 120 characters. When you're done with one text layer, simply click another layer in the text timeline to edit more.
You can change any text layer's size, position or rotation manually by grabbing it in the preview window. You will see handles at the corners of the text that will allow you to manipulate the text. Text can be moved freely around the preview window, so be careful not to drag it out of frame during edit.
You can change the duration of any text layer, or change its position in the timeline by dragging its handles (which look like arrows at head and tail) in the timeline. Text layers can be as long as the video and as short as 2 seconds. You can remove a text layer by hovering over the layer in the timeline and clicking the "X" icon. You can add more text layers by tapping the “Add Text (+)” button at the right of the text timeline. You can add as many text layers as you like, as long as their combined duration is no longer than the video. The process for adding, removing, and trimming text in the timeline is similar to trimming a video for social post, so it should be a familiar experience.
Finally there are several style options at the top of the screen which will allow you to further customize your text. In the style panel, you can select different fonts, change justification, toggle between upper, lower and title case, and change the text and background (if applicable) colors for your text layers. These work exactly like the tools you have likely used in a word processor, Instagram stories, Google Docs, etc.