Hi Bab! I have sent you some helpful information. I hope it makes it easier for you to get rid of the grout. Merry Christmas to you!
I have tried many things as recommended but now use Clorox Toilet bowl cleaner. It is toxic but it certainly does the best job for me. It is a gel, so you put a blob in the corner of four tiles and then spread along the grout lines with a toothbrush. Let sit for ten minutes and then brush again. Wipe up the suds with warm water and vinegar solution. After you have completed all of the tiles, use warm water and vinegar with a mop or a steam mop to remove the residue. I have silver grey grout and it worked well for me.
This is a homemade grout cleaner you can use: https://www.hometalk.com/2122723/cleaning-grout-with-homemade-grout-cleaner
This is the shower cleaner that we use to help keep grout and tiles clean and minimize the mildew - it works on kitchen grout too. Hope this helps! Hugs, Holly
PS - I'm getting ready to release a FREE eBook with recipes for all of my homemade and all-natural cleaners. If you want to know when it's released, you can get it here --> https://pinkfortitude.com/thank/