Three dimensions: For 3D text, click outside the text editor before positioning the letter. Important: Choose the formatting now changing it later will prove difficult. Keyboard shortcut: Press T to select the Text tool. Easier curve selection: Click Make 3D in the Paint 3D sidebar to turn the curve into a 3D object this makes it easier to select just the curve later (if you want to delete it, for example).
Paint 3D keyboard shortcut: Press 2 for 2D shapes. To align text along a curve in Paint 3D for Windows 10/11: