I made a free will online. There are default settings. If I cross something out of my Will and initial it, will my Will be valid?

No.  Any change to a Will must be witnessed and notarized just like a Will.   In addition, while you can leave your estate to someone else as Trustee for a minor child, a conservator is appointed by the Court.   It sounds as though this "will" may be worth what it cost you -- and that it will cost you a great deal more given the high cost of probate in California.  Talk to a local estate planning attorney about a better way to leave things to you daughter (such as a revocable living trust).