Your situation arises because the paragraph styles and fonts that you used in Word 2007 don't match the paragraph styles and fonts of Word 2024. For example: The Heading 1 that you used in Word 2007 is different from the Heading 1 in Word 2024. You may have customized the paragraph styles and fonts of Word 2007 to suit your document, but even if you didn't do that, Microsoft changes the default paragraph styles and fonts of Word over time to match current consumer tastes. You also customized the page margins (to 5.5" x 8.5"). You'll have to re-create all that in Word 2024.
To make the document look exactly the same in Word 2024 you have two choices:
1- Change the paragraph styles and fonts of Word 2024 to match what you had in Word 2007. That will work, but it will also apply those paragraph styles and fonts to new documents in Word 2024, and your documents may look 'old'.
2- Embed the paragraph styles and fonts of your document. That 'locks' the paragraph styles and fonts that you used in Word 2007 to that document alone. That could be a better choice for you, because it will make your document look the way you created it while allowing you to apply Word 2024's updated paragraph styles and fonts to new documents. To embed the paragraph styles and fonts in your Word 2007 document, open the document in your copy of Word 2007 and do this:
1 - Go to File > Options.
2 - Select the Save tab on the left.
3- Scroll down to the bottom and check the box for Embed fonts in the file
4 - Check the sub-box for Embed only the characters used in the document or uncheck it if you plan to edit the text with those fonts on Word 2024 - which will make the file considerably larger.
5 - Select OK and save the document.
That will go a long way toward making your document look the same in Word 2024, but you will have more work to do if you also customized the page settings in Word 2007 like margins and paragraph spacing. You'll have to re-create those in Word 2024. For example, you'll have to change the margins to 5.5" x 8.5". These changes will apply only to your document.
And, you know, you could also re-format your document with Word 2024's paragraph styles, fonts and page settings.