I’m a first timer on this forum so get ready to laugh. How does one make a simple entry to reclassify billable costs from one job to another? Example is moving $1000 from Job 1000 to Job 2000. Example 2 would be how do I accrue billable costs and then reverse them? Thanks,
There is a first time for everything - so no laugh from me 
(assuming you use NAV 5.0 or newer) There is no standard function for this; missing it myself, actually!
Only way in standard NAV is to do it manually: enter Job Journal Lines with negative quantities. and post it to job 1000, then enter journal lines again with positive quantities and post it to job 2000.
You yourself have to make sure that the quantities, costs and prices are correct.
Accrue billalble costs? By using Type=“G/L Account”, perhaps…
Try it out in a CRONUS (=demo) first.