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Without being able to see the SVG, we can still make some guesses. Or if worst comes to worst, and we can't find the problem by guessing, you could attach the SVG file, with some strongly worded copyright, and then delete it immediately after the problem is solved.
When you selected the text, how did you select it? If all the same color changed, that gives me a clue that you might have used the Find dialog, which will select everything of a certain element.
If that's the case, you can use the Selection tool to select only the text.
If you did not use Edit menu > Find/Replace, then perhaps each color of the design is residing on its own layer (a common practice for screenprinting (printing designs on fabric)) and grouped together. And indeed by the title, that must be what you think has happened.
First, to make it easier to control what you're doing, open the Layers menu > Layers (the Layers dialog) and hide all the layers except the one with the text. It's tiny eye icon. If you click it, the eye will be closed, and the layer is hidden.
Now select the text, and I'm guessing you'll see the bounding box (dashed line rectangle) around everything that's still showing. Next Object menu > Ungroup (or there's a button on the command bar, or use a key shortcut (Help menu > Key and Mouse Ref)).
It might be that all the individual objects of that color are just grouped once. Or there may be nested groups. So watch the canvas when you ungroup, and also watch the status bar. When you click on the text, and only the text is selected, you might be ready to change the color. Try it, and just Undo, if we don't have it right yet.
If it's not right yet, this is where we might either need to see the SVG file, or need more info from you.
If you are able to do what you want, then afterwards, do Ctrl + a (select all) and then Object menu > Group (or button on the command bar, or key shortcut). Then make all the layers visible once again, and the file is ready to go back to the printers (or whatever).
Did you want to change the text itself, or just the color of the text? If the name of your post changed, then I guess you'll want to change the text itself?
While it's ungrouped, and either before or after you change the color, look at the status bar while the text is selected. If the status bar says "
Group of...." you'll need to ungroup some more. If it says "
Text...." then you can engage the Text tool
and change it. But if it says "
Path...." you won't be able to edit the text at all (well, not edit
as text). You will only be able to type new text.
Ok, that's a lot of info, so let us know how it goes, and we'll pick up wherever you might be stuck