If the files are not showing in different tabs in the editor, then they might have been undocked. Docking them would open in separate tabs in the editor. Refer the example below to dock/undock files in the editor:
For instance, consider having 2 files : test1.m and test2.m open in the editor.
a) In the top right corner of the Editor window, you can click on a downwards arrow.
b) In order to see both the files at the same time, you may then choose "Undock test1.m".
c) This will open "test1.m' in a separate window and both "test1.m" and "test2.m" will be visible in separate windows.
d) You may reverse this by going to the top right corner of the newly opened window for "test1.m" and choose "Dock test1.m" and this will revert back to the original configuration.
