How to filter items using an input field and a dropdown in PowerApps?

Now select Gallery control and set the Items property to the following formula:

Filter(Accounts, 
 'Industry' = ComboBox3.Selected.Industry||IsBlank(ComboBox3.Selected.Industry), 
 'Relationship Type' = ComboBox2.Selected.'Relationship Type'||
 IsBlank(ComboBox2.Selected.'Relationship Type'), 
 'Preferred Method of Contact' = ComboBox1.Selected.'Preferred Method of Contact'||
 IsBlank(ComboBox1.Selected.'Preferred Method of Contact'))

Above this Gallery control (Blank vertical Gallery), Insert a Blank Horizontal Gallery control (Insert -> Gallery -> Blank horizontal). Select the Blank Horizontal Gallery control and apply this below formula on its Items property as:

Items = Sort(Distinct('Travel Details',Left(Title,1)),Result,Ascending)

Select the Label control and apply this below formula on its FontWeight property as:

FontWeight = If(ThisItem.IsSelected,Bold,Normal)

Select the Gallery control (Blank Horizontal) and change its Fill property to RGBA(91, 170, 59, 1). Select the Label control and apply this below formula on its Fill property as:

Fill = If(ThisItem.IsSelected,Red,Yellow)

Select the Blank vertical Gallery control and apply this below formula on its Items property as:

Items = SortByColumns(Filter('Travel Details',StartsWith(Title,Gallery2.Selected.Result)),"Title")

Next what I want to do is, I want to set a default value from the Gallery control. So that every time the form will display that particular value that you set in the Default property by default (before you select any item in the gallery). If you do not have any formula in Gallery control’s Default property, then the edit form will display the first item by default. (before you select any item in the gallery) To set the Gallery control Default value, Select the Gallery control and apply this below formula on its Default property as:

Default = LookUp('Travel Details',Title="Preetish Chaturvedi")