A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Save your working Word, Excel, and other personal files in either the Mac's Documents folder (Macintosh HD > Users > [Your Username] > Documents) or OneDrive. Leave the Time Machine external drive dedicated to backups.
Choose one primary location for your files. OneDrive is best if you want files synchronized online and available from other devices. Documents on your Mac is best if you prefer local storage and rely on Time Machine for backup. A simple folder structure might include Personal, Financial, Word Documents, Excel Spreadsheets, and Old PC Files subfolders within Documents.
Avoid routinely saving files directly to the Time Machine drive. It is your backup destination, not the normal location for opening and editing documents. Also, do not use the flash drive as permanent storage. Keep it temporarily until you have copied and checked everything.
To move the files from your old PC, connect the flash drive to the Mac, open Finder, and select the flash drive under Locations. Open another Finder window and select either Documents or OneDrive under Finder's Locations section. Create a folder such as Old PC Files, then copy the files from the flash drive into that folder. Open several Word and Excel files to confirm that they copied successfully. Allow Time Machine to complete a backup before erasing or repurposing the flash drive. Standard .docx and .xlsx files can continue to be opened by current Office applications.
To save new Word and Excel files locally, select File > Save As, or press Command+Shift+S. If Office displays an online location, select On My Mac. Select Documents and then the appropriate folder, enter the file name, and select Save. Office for Mac supports saving to the Mac, removable storage, or an online service. Microsoft also recommends saving regularly because AutoRecover does not replace normal saves.
To find a local file later, open Word or Excel and select File > Open > On My Mac. You can also use Recent, then Control-click a file and select Show in Finder.
If your Microsoft 365 subscription includes OneDrive and you want cloud synchronization, sign in to OneDrive on the Mac with your Microsoft account. In Word or Excel, select File > Save As, then Online Locations and OneDrive – Personal. Create or select a folder, enter the file name, and select Save. If OneDrive is absent, select Add a Place > OneDrive, then sign in.
Once you configure Time Machine in your Mac's System Settings > General > Time Machine, it will automatically back up your Mac, including your Documents folder and Word and Excel files, as long as the external drive is connected. Keep the external drive dedicated exclusively to Time Machine backups. Do not manually drag and drop your regular Word or Excel files onto that same drive.
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hth
Marcin