Do I need a new tyre dealer?

Hello all, I had to replace a rim with tyres (front right) at the end of the last winter season due to accident, therefore on the complete front axle new tyres and a rim new. The other axle still had a good 6 mm, so I didn’t touch them. Last week I had my winter tires put on again and since then I have noticeably louder driving noises (yes, I know the winter tires are usually louder, but never so strong). Especially if i I also had the feeling that they didn’t run completely round and therefore I went to the dealer again and wanted to have them balanced out again. He then meant that it wouldn’t be necessary, because that probably comes from the fact that the “older” tyres have now brought forward and the “newer” ones have put on the rear axle because “behind the better tyres”. I always thought it would be better to have the newer ones in front? (PS. Have Quattro Drive) He then said that this would happen over time… Does his statement fit or should I have the axles exchanged again and then look for another dealer? Thank you & Greeting Christian