NEED HELP :(

Eric and Kipp have the right of it. Fix the printer driver or switch to a driver that works like Microsoft Print to PDF as your default printer.

Just a note that both of the things you are doing create Section breaks in Word or change the settings for the whole document. If you are changing Margins for part of your document, change Indents instead. Doing this dramatically reduces the complexity of the file. Change the Indents using a paragraph style, rather than by directly changing them in each paragraph.

• Margins and Indents - Ribbon
• The Importance of Styles in Microsoft Word

P.S. In the future when posting in a help forum, don't use "Need Help" or "Microsoft Word Problem" for the title. Give something about the nature of the problem in the title. It will get you faster responses. For instance, here, an appropriate title might be: Word locks up when I try to change margins or orientation.

The people answering questions here are volunteers, your fellow users. None of us are all-knowing, so we look for questions where we might be able to help. Everyone posting here needs help. This is not a criticism!

Your issue may be caused by Word querying the default printer driver whenever you change margins or orientation. If the printer driver is unavailable, outdated, or misconfigured, Word can freeze or lock up. May try to fix by set a stable default printer (e.g. Microsoft Print to PDF) or update/reset your printer driver.

https://support.microsoft.com/en-us/word/you-receive-an-error-message-when-you-try-to-print-a-document-in-which-margins-of-section-are-set-ou

Word checks the default printer driver when calculating margins, paper size and printable area. If the default printer is offline, unavailable or has a damaged driver, Word can remain stuck on Looking for printer. This is usually a printer or Print Spooler problem rather than a document problem.

First, test with Microsoft Print to PDF:

1. Close Word.
2. Open Settings > Bluetooth & devices > Printers & scanners.
3. Turn off Let Windows manage my default printer.
4. Select Microsoft Print to PDF and choose Set as default.
5. Reopen Word and try changing the margins and orientation.

If Word now works, repair the original printer connection:

1. Cancel any stuck jobs in that printer’s queue.
2. Press Win + R, enter services.msc, and restart Print Spooler.
3. Remove the unavailable printer from Printers & scanners.
4. Install the latest driver from the printer manufacturer and add the printer again. Connect to the company network or VPN first if it is a network printer.

If Word still freezes while Microsoft Print to PDF is the default printer:

1. Press Win + R, enter winword /safe, and test the page layout again.
2. If Safe Mode works, disable Word add-ins under File > Options > Add-ins.
3. If it still fails, run Microsoft 365/Office > Modify > Quick Repair from Installed apps.

Changing the default printer is the most useful first test because it immediately shows whether Word is waiting for a faulty printer driver.