How do I explain to my sister that I have had to take her bank and credit cards away because she is hiding her things?

Do you have her POA? If so, you don’t need to explain a thing to sister. If not, then you may have some trouble over all this.

can you find where the money is hidden? My Dad used to put the money in his sock drawer. I would just take the money from his sock drawer to give to him each week....he was happy..he had money, and in reality we just recirculated the same money week after week.

I wonder if this is where the stories of impish elves come from, trying to explain to an elder who hides things.  'Those elves are at it again...they took it and hid it on you.'  Then have her hunt for it with you.

Just a thought.  Maybe it's time for me to go to bed!

Personally, I'm a bit angered with the "you don't need to explain" response. She's your older sister, and you're trying to respect her questions. It's not that you don't need to explain; it's that she is unable to process the answer because her brain doesn't work like it used to. It's awful to see this ability slip away, especially in someone who was fully competent and independent.

I keep hearing you can't explain things or use rationales with victims because they no longer have the capacity to reason. Dealing with that is easier said than done. What is a discussion except the exchange of facts, opinions, thoughts, logic, etc.? It may be time to start using the "white lies" - as in, "you asked me to deposit the money for you so I did." Or "oh, we took care of that together. Gosh, I'm getting hungry. Do you want something to eat?" That's deflection. Maybe even "I have it safely secured for you. You asked me to hold onto it because your memory is getting a little rusty but every penny you asked me to watch is there." Then deflect.

Having money seems to equal security for some, so removing it will cause anxiety. Maybe small bills that won't matter too much if they get hidden. You'll find them someday - depending on your living situations and she's with or near you. Good luck. Try not to take the anger personally - you're doing the best you can.

I had simular problems with my sister in her early stage
of Alzhiemers I have POA over her health & welfare!
I also got her to go to the bank with me & made her account joint telling her that - if needed I could take care of her affairs!
That worked fortunately for me— she would never remember her pin number & all her close friends did !
As she got worse I changed her pin number & I also would
control what she could take out not that there was much
because of other financial issues that she had forgetting to pay her bills !
That was about six years ago & she is now turning seventy five & is in a nursing home!
Make sure everything is in order before she declines in her health!

Would she realize a gift card is not a credit card? Maybe a small amount or refillable card with a small amount she can spend but not overspend. My mother is the same, we give her $20 when she complains which she promptly hides and forgets and then says someone stole but it’s not going to change.
Don’t argue, don’t explain because she probably will take that as an argument. Just change the subject or if you can’t , leave the room for a bit.

If you go shopping with her all the time can you cancel the card she has, let her keep them when the card is declined you can say ..."I'l take care of this" and you can use an active card. Doing this you will not have to worry about the credit or debit card getting into the wrong hands.
As far as cash goes. I had a difficult time with that with my Husband. He had always used strictly cash for 99.99% of the transactions he did. (used to own his own business and he came from a family that owned a restaurant. so Cash was King) I cleared out his wallet one evening after he went to bed. I removed the cash he had but I did replace some using singles. Looked like a lot more than it really was. It was not long before he actually stopped taking his wallet out to pay for something.

Side note here though. He did take off in the car one day and he did have a credit card in his wallet. After I contacted the police and told them that he had gone missing I called the credit card company and cancelled the card. I did not want someone else getting it somehow and using it. When the police got to the house they asked me about cash and credit cards and when I told the officer that he had little cash and I just cancelled the card they told me that I should have kept it active because it would be easier to track him if he tried to use it. (in the 12 hours he was missing he never tried to use it) ..longest 13 hours of my life!
So it might be good to have an active card on her if you have no other way to track her. (phone or other device that she would have on her)

This phase will pass in time & she won't be this way forever .... it will just feel that way - meanwhile be very careful when throwing out garbage as you don't know where things are hidden - we now figure mom lost many things when she hid money/mail in the used newspaper pile when they where put in recycle box ... also look in towels, under shelf paper [shelves & drawers], matress

Some here have said they put play money is LOs wallets. Depends on how advanced their Dementia is if they know the difference. Its time for you to take the reins. If her Dementia is advancing more and more, she may need an AL. Don't need money there.

Min, she has dementia. Her brain is broken. She can no longer understand and yes, she will blame you and be angry at you.

Is she on any psych meds to help with agitation?

I would just give her small bills. I was giving my mom cash, she always was a “cash” person. I thought she was hiding it in the house. Come to find out she was giving it away to the kid next door. It ended up being thousands of dollars.