How can I transfer text messages from iphone to computer?

The account name says who is writing, so there is no point burying it: I make one of the Windows programs for this. Everything before the last two paragraphs is free and works without me. Taking your closing question first, because it decides the rest.

Yes, you have it right: an iTunes or Finder backup does not let you read individual messages. What is not right is the conclusion above, that it is therefore only good for restoring a phone. Every message is in that backup, with the date, the sender and the photos, sitting in a database under a filename that is a hash of its path, which is why nothing opens it by double clicking. The backup is the correct thing to make. It just needs something to read it, and that is the whole of your problem.

Before you rely on it, one check, because this thread has both halves of a contradiction and nobody has put them together. One reply tells you to switch Messages in iCloud on, another to switch it off. Here is why both appear: with Messages in iCloud on, Apple documents computer backups as not including the messages already stored in iCloud. So you can follow the backup steps perfectly and open the result to find half the thread missing. Make the backup, then confirm it reaches as far back as you need before trusting it. If it does not, either turn Messages in iCloud off and back up again, or scroll the thread on the phone first so the device pulls the history down.

One more thing, since you were told to encrypt the backup, which is the right call for a folder holding years of your conversations. An encrypted backup cannot be opened without its password and Apple cannot recover it. Worth knowing the way out before you need it: Settings, General, Transfer or Reset iPhone, Reset All Settings clears the backup password without touching your data, and the next backup can use a new one.

On your three formats, one is a no. PDF and TXT are normal. Excel is not: what you will be offered is CSV, which Excel opens, and anybody telling you that is the same thing as an Excel export is selling you something. CSV is fine for sorting and counting. It is not a document you would hand to anyone.

The command line tool two people named above does this job and costs nothing, and if you will paste commands into a terminal it is a real answer and you can stop reading here. Two things to notice: the descriptions of it above are two different routes, one reading a Mac's own message database after granting Full Disk Access, the other reading an iTunes backup. And you opened by saying you are not tech savvy and are drowning in complicated options, which is a fair reason to want a window instead of a terminal.

That is where mine sits, with the condition that matters most given you said Windows or Mac: ChatExport is Windows only and there is no Mac build, so if you meant the Mac, it does nothing for you and one of the routes above is your answer. On Windows it opens the local backup, encrypted or not, with the password used and then forgotten rather than stored, and writes a conversation out as a PDF, or as TXT, HTML or CSV. The free download watermarks the pages and stops at the 50 most recent messages in a conversation, so you can see whether it finds your threads before paying anything. The licence is 34.99 USD once, no subscription.

The whole route in the order you would actually do it, backup first and finished file last: https://getchatexport.com/blog/how-to-export-iphone-messages-to-pdf/