You said you didn't try any of the suggestions. What are we supposed to think? No one is being unkind. None of us gets paid to help you and we sometimes need to point that out to new members who come here thinking we will build applications for them for free. When we give you actionable suggestions and you can't be bothered to even try to implement them we might get a little testy. Just because we are not charging for our time doesn't mean that it has no value.
We are happy to help you but you have to put forth some effort. Simply reading the help entry for OpenForm or paying attention to the intellisense when you type in the expression might have given you the clue that the OpenForm Method could open in either Add or Edit mode. You still might need help to work out how best to implement that two-way opening. If you don't understand what we suggest, tell us and we'll go into more detail. I post lots of samples that I have made over the years. Some people even make them on the fly to explain your specific problem.
Any sample I might have posted would have used the method I use. That may be too advanced for you at this point so taking advantage of the built in option of opening a form to add or edit, should solve your problem for now. Please give it a go.