Problems with customizing themes in wordpress. All themes premium and free

I have a problem regarding premium themes of studiopress and also normal themes.
I can’t customize my themes. When I choose a theme and I select the button customize I can’t customize the theme at all.
The window is flashing and it refreshing suddenly without to stop.
For both free themes and premium themes. For all!!!
I choose Side identity or color or background and it return again on the refreshed page.
I can’t modify and customize nothing. I don’t see in the right side of the screen the preview of a theme.
Perhaps this situation is because I’m using a free hosting? Or my wordpress is inftected with malware?
If you don’t understand what I’m saying and what I explain I can record the screen to be well understood.
Please help me.
How to solve the problem? This strange problem. Maybe someone was confronted in the past with the same problem like me.
I will remain grateful to you!
Thank you in advance