Widgets Not Showing

Hello everyone I am having troubles with the widgets they are showing but just one and when i go to widgets to put the other I want to be show it deletes the one that was already there and put up the new one for example: Now I have the recent post in the widget side bar well I want to ad my others like search, pinterest follow button, etc and if y add those my recent post is gone and search is put up and shown … Does anyone knows how to fix that?

Thank you so much in advance
Kristina