One-tailed and Two-tailed tests

I am working on a project where I need to apply F-test and T-test to check for a significant difference. I have a confusion in the one-tail and two-tail tests in excel. If the p-values for both one-tail and two-tail is less than the alpha value which is 0.05, which one should we consider? Is it one-tail or two-tail? Please help me understand this.