When starting up the NCM manager, it shows a logo in the right hand pane. In our system it has been changed to a company logo, but I do not know where to change this setting myself (new company logo). Any ideas?
You can find the logo by looking under the covers, so to speak. With the page displayed showing the logo, right-click on the page and choose View Source in your web browser. Find the html that references the logo (you may need to right-click on the logo and get its properties, to find its name).
Then search for that logo's file name on the web server. Its path should be in the html code for the page, but I'd suspect it would be either in the same directory as the bulk of the page's content, or in a graphics directory that's referenced in the html.
After you discover the image's name and it's location, it's an easy task to put a new graphic in the same directory, and give it the name of the old graphic. Alternately, you could modify the html to remove the reference for the old graphic and put in a line that references the new graphic, remembering to include the path if you aren't putting the graphic in the original directory.
