You might need to adjust some CSS in order to have the Logo rendered correctly, if the size is different than the recommended one. You can modify these values in left-panel.scss, look for the classes .logo-big and .logo-small. Adjust the height in these classes to fit your needs.
The application name which also appears in the title bar can be changed by modifying the appName field in config.js.
Header / Status Bar
The header has a dedicated component which can be found in status-bar.js. You can modify the status-bar <header id="status-bar">...</header> by removing existing components like LanguageSwitcher and UserWidget or by adding different content in the header.
Footer has a dedicated component which can be found in footer.js. You can modify the footer tag by removing the already present links, or simply adding different content next to them.
Every text in this application is coming from a translation file located in langauges.json. This object contains a language block for each language you support in your application. If a block is missing you can duplicate an existing block and modify the block with the language code that is missing.
Some messages might be missing. This is due to fact that they were not yet translated. You can add them manually or use a language editor like POEditor.
You can also override these strings to fit your need, for example, if you would like to have Devices as the name of the menu which we call Things, you have to find the key menu.things and change its value to Devices.