Details. To set the format for time entries in QuickBooks: Click. Click General on the left side, and then click on the Company Preferences tab. Under Time Format select either Decimal (10.20) , or Minutes (10:12) . Click OK. When you select: 1  Decimal QuickBooks automatically interprets time entries as decimal fractions.2  For example, when you enter 4:30, QuickBooks converts your entry to 4.5 (4 and one-half hours). 3  Minutes QuickBooks automatically interprets time entries as hours and minutes.lick General on the left side, and then click on the Company Preferences tab. Under Time Format select either Decimal (10.20) , or Minutes (10:12) . Click OK. When you select: 1  Decimal QuickBooks automatically interprets time entries as decimal fractions.