Mother driving me mad. Do they ever change?

Yes, sadly she will continue to change for the worse, as her brain is broken and it will never get better. In your profile you say that your mom has Alzheimer's/dementia. It sounds like she has some caregivers coming in, but is she really safe to be living on her own?
The best thing you can do for yourself now is educate yourself on Alzheimer's/dementia, as it will help you better understand what your mom is going through, and make you a bit more understanding and patient with her. Like already mentioned, Teepa Snow has some great videos on YouTube, and the book The 36 Hour Day is another great resource.
I used to reference the movie Groundhog Day, a lot when I was caring for my husband, because yes, at times it seemed like I was reliving the same day over and over. Welcome to the world of caregiving and dementia.

Sorry your mom is making you crazy. Sounds like her poor brain is a bit broken with her dementia. You need to change your expectations of what she is capable of doing. She will continue not to listen and not understand or cooperate with the common sense things you are telling her. She might really be cold. Get her to dress more appropriately with a heavy sweater, slippers, etc. instead of keeping the house too hot. They do make up "stupid stories" all the time and it IS quite annoying. My mom gives me the craziest answers to things sometimes. Just take it in stride and don't even ask her to explain why she is doing these strange things. She doesn't know. You're right - it is like Groundhog Day!

Do some reading about dementia. It will help you deal with her. Remove the things that she is doing that might be kind of unsafe. Make the house safe for you to be in as well.

Take lots of deep breathes and change your expectations. You will be much happier!

Yes, they change: they get worse and worse. If the living arrangement is endangering your health, you must try to seek an alternative. You mom has dementia or ALZ (per your profile). She already has lost a lot of her ability to reason, so there's no use in arguing, it will just exhaust you. She also probably has short-term memory impairment so even if she could reason fully, she wouldn't remember what was discussed or agreed upon.

An immediate, temporary solution is to remove all the wet washing supplies to a location she can't find them and hope she doesn't go out to purchase more. You can purchase a free-standing portable room air conditioning unit for your bedroom to cool and dry it. You and your "mum" are probably not in the States so if you can inform on where you live, others on this global site can give recommendations for what social and legal services may be available to you to get relief from her daily care and make future plans.

Watching Teepa Snow videos on YouTube helped me to learn and understand a lot about dementia/ALZ so that I could engage in better and less frustrating ways with my LOs. It helps me to have more patience with and compassion for them as they muddle through their disease.