Apologies for the inconvenience. Below are the solutions to your issues:
Issue 1: Menu Turns Dark on Scroll
To change the background color of the menu when scrolling, add the following CSS to Template Options → Custom Code → Custom CSS:
#sp-header.menu-fixed {
    background: rgba(0, 0, 0, 0.85) !important;
}
Replace rgba(0, 0, 0, 0.85) with the desired color.
Issue 2: Removing the "Footer_Ayuntamiento" Text
In the module settings, there is an option to show or hide the module title. Please set it to Hide.
prnt.sc/LmJbkpGXSqFl
Issue 3: Removing the White Gap Below the Footer
Please add the following CSS code to your Template Options -> Custom Code -> Custom CSS
#sp-footer{
    padding: 0px;
}
Issue 4: Editing Page Titles (Except Home Page)
These titles are controlled in the Menu settings:
- Go to Menus → Your Menu
 
- Open the desired menu item
 
- Navigate to the Page Display tab
 
- Modify the Browser Page Title and adjust other styling settings
prnt.sc/RIMBEpNu-ykv