I assume that you want to bold-face your cross-references to make them stand out strongly in the text. However, this is a dubious practice from a typographic point of view. Rather than bold-facing the cross-references, I'd suggest that you make them into hyperlinks that can be assigned a color. To do this, start by loading the hyperref package with the
colorlinks option set. Then, use the
\autoref command that's provided by the
hyperref package to create colored hyperlinks to the objects being cross-referenced. Note that the
\autoref command is what one might term fully dynamic: it typesets both the type (such as equation, figure, table, section, etc.) and the number of the cross-referenced object. By using the
\autoref command, the hyperlink "target" (the part that's colored) will be highly visible, because it consists of both the type and number of the item being cross-referenced.
An even more flexible and powerful cross-referencing command than
\cref, provided by the cleveref package; I suggest that you load the
cleveref package the
nameinlink option set. (Even if you do use
\cref, I still recommend you also load the
hyperref package with the
colorlinks option set. If you load both
cleveref, be sure to load
hyperref first.) Like
\cref is fully dynamic; the
nameinlink option forces the link to consist of both the item's type and number. Unlike
\cref lets you create cross-references to multiple items of the same type (e.g., equations) and even multiple items of differing types all in one cross-referencing command; the
cleveref package will nicely sort and typeset the cross-references being generated without the user having to worry about such details.
For much more on various cross-referencing commands and packages in general, and the
cleveref packages in particular, see the answers to the question Cross-reference packages: which to use, which conflict?