Print Speed and Times in Cura 21.08

I’m using Cura supplied by Lulzbot for my Taz 6 printer but I’ve noticed that changing the print speed makes no difference to the print time and the only way I can get the printer to speed up is by adjusted it manually while it is printing. Am I missing something? I have it installed on a another PC and it has the same problem. It would be good to get a more accurate idea of print time and speed up the printer as at the moment it seems to be just defaulting to 15mm/s and taking a heck of a long time to print anything. I have attached a screenshot of settings in Cura if that helps anyone. Thanks.