@Rea_M 

I have probably submitted this with many other people a couple dozen times over the course of the last 3 years. The suggestions feedback system seems to just go right in the trash bin at QuickBooks. 

“On the other hand, I can see how the benefit of being able to use and print billable entries in HH:MM format on invoices”

I think you are misunderstanding the problem. The time DOES print on the invoice in HH:MM. this is absolutely useless to literally everyone in the world. The time shows in decimal when editing the invoice line item but then changes to HH:MM when printed/emailed. 

I am 100% this is a bug/glitch but QuickBooks will not fix it. On the desktop version as @Thayer2 @stated, you can select that you want it printed out in decimal but the option does not exist for online version. I spend about 4 hours a week manually creating emails a week losing ~$1000  a month in my time having to do this task instead of it being and automated task. 

ps, how much would it cost for me to just pay one of your programmers to finally just fix this!?