Problems with passwords & saving data & installing theme

[aloynium]

Hi I have a problem with the prestashop I just installed, with a few problems below.

 

1) I can't save the data, why is that? For example, if I try to delete 1 product from the default theme, it doesn't save when I click 'Save'.

 

2) I have to keep logging in when I change section, why is that?

 

Are both 1 and 2 cache related? If so how can I make changes and what changes should I make? I tried entering the caching page to make changes but as mentioned before, no 'saving' is possible? If it is on my server side what should I do?

 

3) There are instructions to install the theme, but I can't find the 'select file' to upload in order to change it. I already have the theme but before I can upload it, I cannot change anything.

 

Any help offered will be much appreciated. I'm very new to this so hope you can guide me gradually. Thanks.