For many projects that GMS produces the deliverable to a client will come in the form of a PDF file.
The reasons for this are many.
1- a PDF embeds all font files needed to make a particular design show up correctly
2- a PDF holds a layout perfectly, including pagination and images.
3- a PDF can be either interactive or offset print ready which works well for most uses.
The issue with a PDF file is that for the most part it is pretty much “set in stone” when it comes to making other changes to it after the PDF has been created. Since for many design reasons a PDF is originally created in a wide range of software programs from Microsoft Word, Adobe InDesign, Adobe Photoshop, Corel Draw and more. So unless you have those original software programs on your computer you’re going to have to ask the person(s) who created it to make changes. For significant alterations it makes sense to use your original resource to make a change but for a minor change (numbers, names or small tweaks) you might be able to do it yourself.
If you have the full version of Adobe Acrobat you can make minor adjustments to text on your advanced PDF layout. It requires some moderate computer skills but it is not all that difficult. The following video helps explain how this is done. Note that the version of Acrobat used in this video is not current, but the tools are similar in whichever version you may have. Feel free to view.