Min and max track

Hi team

I am working in excel user form and need support on my below query

Textbox2 is Input 
Textbox4 is Input 


i have textbox1 and textbox2
i want to display the value of textbox2 in Textbox1 only if the value of Textbox1 is less then textbox2. 

similarly 
i have textbox3 and textbox4
i want to display the value of textbox4 in Textbox3 only if the value of Textbox4 is greater then textbox3. 

please help.