I have problems to update the software

You may need to upgrade macOS to update Safari.

1.  Check compatibility

      To confirm compatibility before downloading, check the minimum requirements for 

macOS Catalina, Mojave, High Sierra, Sierra, El Capitan, or Yosemite.

      You can also find compatibility information on the product-ID page for

 MacBook Pro, MacBook Air, MacBook, iMac, Mac mini, or Mac Pro.

2.  Please read this section carefully

      Section: Download macOS

      https://support.apple.com/en-us/HT211683

     Install macOS upgrade.

     https://support.apple.com/en-us/HT201475

Related:

https://support.apple.com/en-us/HT201541

To be specific, it is not possible to upgrade Safari individually as it is installed as part of the Mac's operating system. Upgrading the OS will normally upgrade Safari. This is not an unusual complaint. Here is the reason for your problem. Web site engineers write their software to work with specific browsers and specific versions of them. For some reason, they often choose to not be compliant with Safari. This is not an Apple problem as Apple has no control over the millions of web sites on the internet. You can hope that your web site's developers eventually update their site to work with Safari, or you can use another browser that does work, such as Firefox or Chrome. Also, if you do update your operating system, that does not guarantee that Safari will be compliant with the site's software.