Microsoft changes default settings for a variety of reasons, but some recent key changes will keep us safer from attacks, specifically ransomware. This includes blocking macros by default, limiting native tools used by attackers, and activating Credential Guard by default.
Blocking Office 365 macros
The first major change in an Office 365 default blocks internet macros by default. Launching malicious macros is a common way that attackers can gain access to computer systems and launch lateral attacks. Specially, Visual Basic Application obtained from the internet will be blocked by default. Setting this as the default will mean that you’ll be better protected. If you’ve downloaded macro-based templates from websites, mark these files as trusted and remove the “mark of the web” from the files to ensure that they continue to work.