Go into the Admin CP and expand "Styles & Templates". Click "Search in Templates". Choose one of the styles that the error occurs when you change from, enter "footer" in the textfield and pick "Yes" at "Search Titles Only". In the list that appears, double click the one that's just called "footer". You can paste the whole thing if you want, or you can find the specific code block. It should say "quickchooser" or something in the block - only a couple of lines.