Help! How to change images from CACHE

Hello!
I have a question. I was overwriting my images from the homepage, the ones that have the products below with prices.
Also I overwrite the images that were in the other page when I clicked that images.
Example:

http://www.hankip.com.pe/IMAGE1.png
http://www.hankip.com.pe/IMAGE2.png

Until that everything was Ok. But after 1 day, the images from the homepage were exactly like the images that were in the other page. I don't know why... They change themselves... How do I do to make the image to stay in their place and not change by themselves??

Thank you!

Hi,
1) First, check if you have any cache settings in your Joomla (Global Configuration) or in Template settings
2) Second, If you upload those images by FTP (as you show url) and they are gone, you have to ask Hosting support. Joomla can not delete files by them-self.