Changes made within the body of a Will are NOT effective. The only way to change to a Will is to sign a documents called a Codicil or sign a new Will. If you do a Codicil, it must be signed with the same formality as the Will was signed. Those formalities vary from state to state. For example, in Ohio, the Will must be signed and dated at the end, witnessed by two competent adults who sign as witnesses and place their addresses at the end after the signing. Some state require three witnesses. Some state require a notary. Some states require a "self-attestation clause" at the end. Sometimes the witness can be the notary, and sometimes not. If you fail to sign the Codicil correctly, it will be invalid. Maybe you can't afford NOT to hire an attorney.
Do not rely on an internet form that promises "good in all states." That is likely untrue. If you want to proceed without an attorney, be sure you know for sure the state laws for signing the Will or Codicil and follow the rules. Good Luck!