To change the logos you can change it from the Wazuh UI.
Click Wazuh main menu and then on Settings -> Configuration.Once there, scroll down to the Logo Customization section o use the filter to select logo customization.
The path where you have to add you custom logo depends on the installation type, in case of Wazuh Dashboard the path is:
/usr/share/wazuh-dashboard/plugins/wazuh/public/assets/You can add the logo in svg, png o jpg formats.
Once done, please restart the Wazuh-dashboard service:
systemctl restart wazuh-dashboard
You can check the pictures of how the options look on the dashboard.
Regarding changing text, it will depend on what you want to modify.
I hope this helps you with your question.
Cheers.