Running into errors while using Excel can be frustrating, especially when macros are involved. Macros can help automate repetitive tasks, making work much more efficient. However, at times, Microsoft Excel might block macros due to certain settings or issues, resulting in a ‘Microsoft has blocked macros from running because the source of this file is untrusted’ error. This error usually pops up due to security concerns. Here are the top six fixes that can help you resolve this error.

1. Trust Center Settings: One of the quickest fixes to consider is changing the Trust Center settings within Excel. Navigate to File > Options > Trust Center > Trust Center Settings and select the ‘Macro Settings’ option. Make sure to select an option that enables all macros or prompts their use. Remember, this should be done cautiously as enabling all macros can pose a security risk.

2. Trusted Locations: Adding the file location to the list of trusted locations can resolve this error. Within the Trust Center settings navigate to ‘Trusted Locations’ and add a new location where your macro-enabled files are stored. This tells Excel to trust all files from that particular folder.

3. File Block Settings: Under Trust Center settings, check out the ‘File Block Settings’ tab and ensure that you uncheck the file types that you want to open without restrictions.

4. Digital Signature: If possible, use a digitally signed macro from a trusted publisher. Once a publisher has been trusted, any future macros from them will run without interruption.

5. Unblock the File: Sometimes, files downloaded from the internet are blocked by default for security purposes. To unblock a file, right-click on it within File Explorer, select ‘Properties’, go to the ‘General’ tab and click on ‘Unblock’ at the bottom.

6. Update Excel: It’s essential to keep your software updated. Check for any available updates for Microsoft Office since newer updates may resolve bug-related issues causing such errors.

While resolving this error, always ensure that you understand the risks involved with enabling macros, especially from unknown sources as they can be used maliciously. Therefore, it’s crucial to follow these steps while keeping your system’s security in mind.