Push for example Talk on Global channel key. Notice that you're talking now but when you release it the channel changes back to what it was before. Now if you want to type in Global channel you need to browse through the channels.
My solution would be like this:
Press for example Switch to Global channel. Now you can type in it or just use Push to Talk to talk in it. Simple. Way faster channel browsing for people who can use number keys for example for this.