how do I do this?
I’d like it to read 5 in the multi-measure rest
thanks 
There must be something at the start of bar 5, or perhaps in bar 5, that is causing the multi-bar rest to break. Make sure you have signposts visible by switching off View > Signposts > Hide Signposts, and hopefully the problem will become apparent.
If it doesn’t, attach the project (or a cut-down section of it sufficient to reproduce the problem) here .