It sounds like Excel may be interpreting the numbers you entered as a date or time format. One possible solution is to format the cells as "General" or "Number" instead of "Currency" or "Accounting." You can do this by selecting the cells you want to format, then right-clicking and selecting "Format Cells." In the "Number" tab, choose "General" or "Number" and click "OK." This should display the numbers as you entered them without any extra decimals or currency symbols.
If this does not solve the issue, you can try resetting the Excel preferences by deleting the com.microsoft.Excel.plist file from the ~/Library/Preferences folder. To do this, go to Finder, select "Go" from the top menu bar, and choose "Go to Folder." Then type in ~/Library/Preferences and hit enter. Find the com.microsoft.Excel.plist file and drag it to the trash. Restart Excel and see if the issue persists.
If none of these solutions work, it may be worth reaching out to Microsoft support for further assistance.