Certain forms were made with this different software. LiveCycle Designer (note the name especially the V) is the only tool to redesign these forms. Note that ordinary edits are impossible, you have to be a form designer.
NB such forms are made for FILLING and you can do that.
Let me add just one thing to what TSN already stated:
Up to Acrobat version X, if you had the "Pro" version, it came bundled with LiveCycle Designer. If you upgraded from an earlier Acrobat version, and you still have access to that license (and a computer that it will run on), you may be able to install your old version of Acrobat and use LiveCycle Designer to edit your form. Keep in mind that this might not work if the version of LiveCycle Designer used to create this form is newer than what came with your old version of Acrobat.