The way Safari is updated is by upgrading your computer's software. The reason for this is because Safari is installed as part of the operating system. It cannot normally be individually installed. Incidentally, a newer version of Safari does not always work with every web site. Sometimes it is necessary to install another browser such as Firefox or one of the many browsers available from the Apple App Store to use with certain web sites. They are individually installed and upgraded.
You have told us nothing about what your issue is so there is little that we can offer in response.