Hello Clemens Wilhelm
Unfortunately it is not possible to change the order of the segments in Editor view. The content will be displayed in the same order as it is found in the source file.
So in short you would have to change the source file itself to display the content in such order.
The workaround I can imagine would be - if you're looking at translating an Excel file, and if it's really necessary to have the segments ordered alphabetically for the translation - is to save the source as, order the cells in the copy of the source file alphabetically and translate it in Studio. And update your memory with the translation, take the original file (un-ordered) and pre-translate it using the memory.
Greta Magyar - Customer Success Representative - SDL