Getting into edit mode in a form in the database

I can’t back into edit / design mode on a form I’ve created and edited several times previously (as recent as yesterday). When I open the form the “design mode” icons are there but they’re greyed out and don’t work.

Sorry but I think it’s working now. Previously when I went to edit the form choosing edit from the dropdown, it wasn’t working so I would open and then click the design mode button. Now I just tried going into edit mode directly from the dropdown and all my icons are active.