I am using SharePoint 2013. When I log in in my site it asks me to do so 3 times. I think the reason behind it is because I am using two apps, so it once asks to log in into the page and later asks for each app. When I log in just once it keeps me logged in but in the space where the apps were supposed to be, is only one error message about the certificate. Moreover it asks me to log in whenever I have a document and try to open it. Is there any way I can get rid of these problems? It would be good if word and excel automatically import the credentials from the SharePoint account which is logged on.
Add the SharePoint site to the intranet zone or trusted sites zone (browser settings).
If that does not help make sure that all the loaded content including images, css files, etc... are all loaded from the same domain.
In what internet zone is your SharePoint site accessed? The normal zone for your SharePoint is the Local Intranet zone.
You can add your SharePoint site to this zone using manual Internet Explorer settings or using a Policy.
Try verifying if your SharePoint site is added to the Local Intranet: Internet Options > Security > Local Intranet > Sites > Advanced.