If you never read documentation

You must read this section before editing files in the WYSIWYG mode. By default, the WYSIWYG editing mode is not used for all file types. This is due to the necessity of adjusting some important, yet uncomplicated settings. For the WYSIWYG editor to work properly and also for your files not to be damaged, please configure Site-UP giving attention to the 'Beginning of the HTML fragment' and 'End of the HTML fragment' of the 'WYSIWYG editor support' section (configuration mode). We also recommend that you create a copy of a file you will be able to experiment with to make sure the WYSIWYG HTML editor works properly.

indexsoft Site-Up has many possibilities for its configuration.  If you think that indexsoft Site-UP lacks some features you need, please consult the 'Configuration' section or contact indexsoft before making the decision about uninstalling the program.