• How change the orders the categories in the menu (gallery)?
Drag and drop in your Imgaevue admin interface. Optionally, you can use the "sorting options"
• Unable to load images (tested with safari / firefox) is that a problem in mac?(images are in jpg)
Your gallery works fine here. Do you have a specific link to an image that dont load?
https://d.pr/bsoK
• for the home page, how to center the image and put it in full format?
Not sure what you mean. The text on your page is already centered, and also in our demo gallery, the startimage is also centered on the startpage:
https://www.photo.gallery/demo/x2/ - Full format? You mean full screen? The user has to click the fullscreen button (and you can make it as a link as in the demo above).
• Is it possible to add text, at the top or bottom of the home page?
You can add your own SWF and set it as a background image above the other background ... and align it to either top or bottom. This would require you to make something in SWF. Optionally, you can create some html and add it to settings -> seo.counters ...
• when I want add a picture's description, it does not appear on the site
You have set your images to "fitstage", so there is not room for titles or description above the image. You need to figure out where to display the texts, perhaps overlaying the image? That is why we have default settings "fitmargin". If you are changing it, you need to make a plan for where you want the descriptions to display instead ...
• put a link back "home page", on each category, is this possible?
Can't you just have "home" link available in the menu? Just unhide your startpage. Optionally, you would have to add a link in your folder descriptions that display in thumbnails mode.
• how to keep the scrolling images visible without disappears?
Go to admin -> settings -> controls.maincontrols.autohide - Uncheck it.
• how to write the text "slide show" next to the arrow?
Next to what arrow? All items in main control have text displayed when user hovers mouse over them ...
• how to redirect the link to another window?
What link? When adding links in descriptions, use target="_blank" like this:
<a href="https://www.photo.gallery" target="_blank">Imagevue</a>